The Fourth Amendment held to forbid Border Patrol officers, in
the absence of consent or probable cause, to search private
vehicles at traffic checkpoints removed from the border and its
functional equivalents, and for this purpose there is no difference
between a checkpoint and a roving patrol. Almeida-Sanchez v.
United States, 413 U. S. 266
followed. Pp. 422 U. S.
POWELL, J., delivered the opinion of the Court, in which
DOUGLAS, BRENNAN, STEWART, MARSHALL, and REHNQUIST, JJ., joined.
REHNQUIST, J., filed a concurring opinion, post,
422 U. S. 898
BURGER, C.J., filed an opinion concurring in the judgment, in which
BLACKMUN, J., joined, post,
p. 422 U. S. 899
WHITE, J., filed an opinion concurring in the judgment, in which
BLACKMUN, J., joined, post,
p. 422 U. S.
MR. JUSTICE POWELL delivered the opinion of the Court.
Border Patrol officers stopped respondent's car for a routine
immigration search at the traffic checkpoint
Page 422 U. S. 892
on Interstate Highway 5 at San Clemente, Cal., on November 12,
1973. They found three aliens concealed in the trunk, and
respondent was convicted on three counts of knowingly transporting
aliens who were in the country illegally. The Court of Appeals for
the Ninth Circuit reversed the conviction in an unreported opinion,
relying on dictum in its opinion in United States v.
500 F.2d 960 (CA9 1974), aff'd, post,
422 U. S. 916
the effect that our decision in Almeida-Sanchez v. United
States, 413 U. S. 266
(1873), required probable cause for all vehicle searches in the
border area, whether conducted by roving patrols or at traffic
checkpoints. We granted certiorari. 419 U.S. 824 (1974).
Nothing in this record suggests that the Border Patrol officers
had any special reason to suspect that respondent's car was
carrying concealed aliens. Nor does the Government contend that the
San Clemente checkpoint is a functional equivalent of the border.
Brief for United States 16. The only question for decision is
whether vehicle searches at traffic checkpoints, like the roving
patrol search in Almeida-Sanchez,
must be based on
we rejected the Government's
contention that the Nation's strong interest in controlling
immigration and the practical difficulties of policing the Mexican
border combined to justify dispensing with both warrant and
probable cause for vehicle searches by roving patrols near the
border. The facts did not require us to decide whether the same
rule would apply to traffic checkpoints, which differ from roving
patrols in several important respects. 413 U.S. at 413 U. S. 273
at 413 U. S. 276
(POWELL, J., concurring).
A consolidated proceeding on motions to suppress in this and
similar cases produced an extensive factual
Page 422 U. S. 893
record on the operation of traffic checkpoints in southern
California. United States v. Baca, 368 F.
(SD Cal 1973). The San Clemente checkpoint is 62 air
miles and 66 road miles north of the Mexican border. It is on the
principal highway between San Diego and Los Angeles, and over 10
million vehicles pass the checkpoint in a year. United States
514 F.2d 308, 312 (CA9 1975). The District
Court in Baca described the checkpoint as follows:
"Approximately one mile south of the checkpoint is a large black
on yellow sign with flashing yellow lights over the highway stating
'ALL VEHICLES, STOP AHEAD, 1 MILE.' Three-quarters of a mile
further north are two black on yellow signs suspended over the
highway with flashing lights stating 'WATCH FOR BRAKE LIGHTS.' At
the checkpoint, which is also the location of a State of California
weighing station, are two large signs with flashing red lights
suspended over the highway. These signs each state 'STOP HERE --
U.S. OFFICERS.' Placed on the highway are a number of orange
traffic cones funneling traffic into two lanes where a Border
Patrol agent in full dress uniform, standing behind a white on red
'STOP' sign checks traffic. Blocking traffic in the unused lanes
are official U.S. Border Patrol vehicles with flashing red lights.
In addition, there is a permanent building which houses the Border
Patrol office and temporary detention facilities. There are also
floodlights for nighttime operation."
368 F. Supp. at 410-411.
The Border Patrol would prefer to keep this checkpoint in
operation continuously, but bad weather, heavy traffic, and
personnel shortages keep it closed about one-third of the time.
When it is open, officers screen all northbound traffic. If
anything about a vehicle or its
Page 422 U. S. 894
occupants leads an officer to suspect that it may be carrying
aliens, he will stop the car and ask the occupants about their
citizenship. If the officer's suspicion persists, or if the
questioning enhances it, he will "inspect" portions of the car in
which an alien might hide. [Footnote 1
] Operations at other checkpoints are similar,
although the traffic at some is light enough that officers can stop
all vehicles for questioning and routinely inspect more of
The Government maintains that these characteristics justify
dispensing with probable cause at traffic checkpoints despite the
Court's holding in Almeida-Sanchez.
It gives essentially
two reasons for distinguishing that case. First, a checkpoint
officer's discretion in deciding which cars to search is limited by
the location of the checkpoint. That location is determined by
high-level Border Patrol officials, using criteria that include the
degree of inconvenience to the public and the potential for safe
operation, as well as the potential for detecting and deterring the
illegal movement of aliens. By contrast, officers on roving patrol
were theoretically free before Almeida-Sanchez
to stop and
search any car within 100 miles of the border. Second, the
circumstances surrounding a checkpoint stop and search are far less
intrusive than those attending a roving patrol stop. Roving patrols
often operate at night on seldom-traveled road, and their approach
may frighten motorists. At
Page 422 U. S. 895
traffic checkpoints, the motorist can see that other vehicles
are being stopped, he can see visible signs of the officers'
authority, and he is much less likely to be frightened or annoyed
by the intrusion.
These differences are relevant to the constitutional issue,
since the central concern of the Fourth Amendment is to protect
liberty and privacy from arbitrary and oppressive interference by
government officials. Camara v. Municipal Court,
387 U. S. 523
387 U. S. 528
(1967); Schmerber v. California, 384 U.
, 384 U. S. 767
(1966). The Fourth Amendment's requirement that searches and
seizures be reasonable also may limit police use of unnecessarily
frightening or offensive methods of surveillance and investigation.
See, e.g., Terry v. Ohio, 392 U. S.
, 392 U. S. 16
(1968); Camara, supra
at 387 U. S. 531
at 384 U. S.
-772. While the differences between a roving patrol
and a checkpoint would be significant in determining the propriety
of the stop, which is considerably less intrusive than a search,
Terry v. Ohio, supra,
they do not appear to make any
difference in the search itself. The greater regularity attending
the stop does not mitigate the invasion of privacy that a search
entails. Nor do checkpoint procedures significantly reduce the
likelihood of embarrassment. Motorists whose cars are searched,
unlike those who are only questioned, may not be reassured by
seeing that the Border Patrol searches other cars as well. Where
only a few are singled out for a search, as at San Clemente,
motorists may find the searches especially offensive. See
Note, Border Searches and the Fourth Amendment, 77 Yale L.J. 1007,
Moreover, we are not persuaded that the checkpoint limits to any
meaningful extent the officer's discretion to select cars for
search. The record in the consolidated proceeding indicates that
only about 3% of the cars that
Page 422 U. S. 896
pass the San Clemente checkpoint are stopped for either
questioning or a search, 368 F. Supp. at 411. Throughout the
system, fewer than 3% of the vehicles that passed through
checkpoints in 1974 were searched, Brief for United States 29, and
no checkpoint involved in Baca
reported a search rate of
more than 10% or 15%. 368 F. Supp. at 412-415. It is apparent from
these figures that checkpoint officers exercise a substantial
degree of discretion in deciding which cars to search. The
Government maintains that they voluntarily exercise that discretion
with restraint and search only vehicles that arouse their
suspicion, and it insists the officers should be free of judicial
oversight of any kind. Viewed realistically, this position would
authorize the Border Patrol to search vehicles at random, for no
officer ever would have to justify his decision to search a
This degree of discretion to search private automobiles is not
consistent with the Fourth Amendment. A search, even of an
automobile, is a substantial invasion of privacy. [Footnote 2
] To protect that privacy from
official arbitrariness, the Court always has regarded probable
cause as the minimum requirement for a lawful search.
413 U.S. at 413 U. S.
-270; Chambers v. Maroney, 399 U. S.
, 399 U. S. 51
(1970). We are not persuaded that the differences between roving
patrols and traffic checkpoints justify dispensing in this case
with the safeguards we required in Almeida-Sanchez.
therefore follow that decision and hold that, at traffic
checkpoints removed from the border and its functional
Page 422 U. S. 897
officers may not search private vehicles without consent or
probable cause. [Footnote
The Government lists in its reply brief some of the factors on
which officers have relied in deciding which cars to search. They
include the number of persons in a vehicle, the appearance and
behavior of the driver and passengers, their inability to speak
English, the responses they give to officers' questions, the nature
of the vehicle, and indications that it may be heavily loaded. All
of these factors properly may be taken into account in deciding
whether there is probable cause to search a particular vehicle. In
addition, as we note today in United States v. Brignoni-Ponce,
at 422 U. S.
-885, the officers are entitled to draw reasonable
inferences from these facts in light of their knowledge of the area
and their prior experience with aliens and smugglers. In this case,
however, the officers advanced no special reasons for believing
respondent's vehicle contained
Page 422 U. S. 898
aliens. The absence of probable cause makes the search
The Government also contends that, even if
applies to checkpoint searches, the Court
of Appeals erred in voiding this search because it occurred after
the date of decision in Almeida-Sanchez
but before the
Court of Appeals stated in United States v. Bowen, supra,
that it would require probable cause for checkpoint searches.
Examination of the Government's brief in the Ninth Circuit
indicates that it did not raise this question below. On the
contrary, it represented to the court that the decision in
would be "determinative of the issues in this case."
We therefore decline to consider this issue, which was raised for
the first time in the petition for certiorari.
Such places typically include the trunk, under the hood, and
beneath the chassis. If the vehicle is a truck, a camper, or the
like, the officer inspects the enclosed portion as well. But an
immigration inspection is not always so confined. In
Almeida-Sanchez v. United States, 413 U.
(1973), the officer removed the back seat cushion
because there were reports that aliens had been found seated
upright, behind seats from which the springs had been removed.
at 413 U. S. 286
(WHITE, J., dissenting).
The degree of the invasion of privacy in an automobile search
may vary with the circumstances, as there are significant
differences between "an automobile and a home or office."
Chambers v. Maroney, 399 U. S. 42
399 U. S. 48
(1970); Almeida-Sanchez v. United States,
413 U.S. at
413 U. S. 279
(POWELL, J., concurring).
Not every aspect of a routine automobile "inspection," as
described in n
necessarily constitutes a "search" for purposes of
the Fourth Amendment. There is no occasion in this case to define
the exact limits of an automobile "search."
Nor do we have occasion to decide whether a warrant could issue
approving checkpoint searches based on information about the area
as a whole, in the absence of cause to believe that a particular
car is carrying concealed aliens, because the officers had no such
warrant in this case and had not tried to obtain one. See
Almeida-Sanchez v. United States, supra
at 413 U. S. 275
(POWELL, J., concurring); Camara v. Municipal Court,
387 U. S. 523
(1967). We also need not decide whether checkpoints and roving
patrols must be treated the same for all purposes, or whether
Border Patrol officers may lawfully stop motorists for questioning
at an established checkpoint without reason to believe that a
particular vehicle is carrying aliens. Cf. United States v.
p. 422 U. S. 873
do we suggest that probable cause would be required for all
inspections of private motor vehicles. It is quite possible, for
example, that different considerations would apply to routine
safety inspections required as a condition of road use.
MR. JUSTICE REHNQUIST, concurring.
I joined the dissent of my Brother WHITE in Almeida-Sanchez
v. United States, 413 U. S. 266
(1973), and recognize that the present decision is an extension of
the unsound rule announced in that case. I nonetheless join the
opinion of the Court, because a majority of the Court still adheres
and because I agree with the Court's
analysis of the significance of the Government's proffered
distinctions between roving and fixed checkpoint searches.
I wish to stress, however, that the Court's opinion is confined
to full searches, and does not extend to fixed checkpoint stops for
the purpose of inquiring about citizenship. Such stops involve only
a modest intrusion, are not likely to be frightening or
significantly annoying, are regularized by the fixed situs, and
effectively serve the important national interest in controlling
Page 422 U. S. 899
entry. I do not regard such stops as unreasonable under the
Fourth Amendment, whether or not accompanied by "reasonable
suspicion" that a particular vehicle is involved in immigration
violations, cf. United States v. Brignoni-Ponce, ante
422 U. S. 873
I do not understand today's opinion to cast doubt upon their
MR. CHIEF JUSTICE BURGER, with whom MR. JUSTICE BLACKMUN joins,
concurring in the judgment. *
Like MR. JUSTICE WHITE, I can, at most, do no more than concur
in the judgment. As the Fourth Amendment now has been interpreted
by the Court, it seems that the Immigration and Naturalization
Service is powerless to stop the tide of illegal aliens -- and
dangerous drugs -- that daily and freely crosses our 2,000-mile
southern boundary. [Footnote 2/1
Perhaps these decisions will be seen in perspective as but another
example of a society seemingly impotent to deal with massive
lawlessness. In that sense, history may view us as prisoners of our
own traditional and appropriate concern for individual rights,
unable -- or unwilling -- to apply the concept of reasonableness
explicit in the Fourth Amendment in order to develop a rational
accommodation between those rights and the literal safety of the
Page 422 U. S. 900
Given today's decisions, it would appear that, absent
legislative action, nothing less than a massive force of guards
could adequately protect our southern border. [Footnote 2/2
] To establish hundreds of checkpoints
with enlarged border forces so as to stop literally every car and
pedestrian at every border checkpoint, however, would doubtless
impede the flow of commerce and travel between this country and
Mexico. Moreover, it is uncertain whether stringent penalties for
employment of illegal aliens, and rigid requirements for proof of
legal entry before employment, would help solve the problems, but
those remedies have not been tried.
I would hope that, when we next deal with this problem, we give
greater weight to the reality that the Fourth Amendment prohibits
searches and seizures" and to the
frequent admonition that reasonableness must take into account all
the circumstances and balance the rights of the individual with the
needs of society. See, e.g., Terry v. Ohio, 392 U. S.
(1968); Elkins v. United States, 364 U.
(1960); United States v. Biswell,
406 U. S. 311
* [This opinion applies also to No. 74-114, United States v
p. 422 U. S.
The Court today recognizes that as many as 12 million illegal
aliens are now present in this country. United States v.
at 422 U. S. 878
and n. 4. See also
U.S. News & World Report, July 22,
1974, p. 27; id.
Dec. 9, 1974, p. 77. By all indications,
the problem will increase in the future, not abate. United
States v. Baca, 368 F.
, 402 403 (SD Cal.1973). In the Baca
Judge Turrentine conducted a thorough review of the entire problem
and the present Government response. Appended to this opinion is an
app|>excerpt from Judge Turrentine's Baca
opinion describing the illegal alien problem and the law
For example, testimony in the Baca
that a complement of 21,000 officers would be needed to control
adequately the 75 miles of border in the El Centro sector
APPENDIX TO OPINION OF BURGER, C.J.,
CONCURRING IN THE JUDGMENT
Excerpt from Judge Turrentine's opinion in United
v. Baca, 368 F.
Supp. 398, 402-408 (SD Cal.1973)
THE ILLEGAL ALIEN PROBLEM
The United States through legislative action has determined that
it is in the best interest of the nation to limit the number of
persons who can legally immigrate into the country in any given
year. These controls
Page 422 U. S. 901
reflect in part a Congressional intent to protect the American
labor market from an influx of foreign labor. Karnuth v. United
States, 279 U. S. 231
. (1929); § 201(a) of the Immigration and Nationality Act of 1952,
66 Stat. 163, as amended by the Act of October 3, 1965, 79 Stat.
911, 8 U.S.C. § 1151(a).
Under this policy of limited admission, 385,685 new immigrants
entered the United States legally during fiscal year 1972. Since
July 1, 1968, the law has established an annual quota of 120,000
persons for the independent countries of the Western Hemisphere.
Included within this quota are immigrants from the Republic of
Mexico, who, in fiscal year 1972, totalled 64,040. 1972 Annual
Report, Immigration and Naturalization Service, p. 2, 28.
Currently, illegal aliens are in residence within the United
States in numbers which, while not susceptible of exact
measurement, are estimated to be in the vicinity of 800,000 to over
one million. Department of Justice, Special Study Group on Illegal
Immigrants from Mexico, A Program for Effective And Humane Action
on Illegal Mexican Immigrants, 6 (1973), [hereinafter cited as
Of these illegal aliens, approximately 85 percent are citizens
of Mexico. Cramton Rpt.
at 6. They are industrious, proud
and hard-working people who enter this country for the purpose of
earning wages, accumulating savings, and returning or sending their
savings home to Mexico.
Since 1970, the number of illegal Mexican aliens in the United
States who have been apprehended has been growing at a rate in
excess of 20 percent per year. Cramton Rpt.
The increasingly large numbers of Mexican nationals seeking to
illegally enter this country reflects the substantial
Page 422 U. S. 902
unemployment and underemployment in Mexico -- fueled by one of
the highest birth rates in the world. Moreover, Mexican employment
statistics are not likely to improve dramatically, since fully 45
percent of Mexico's population is under 15 years of age and,
therefore, will soon be attempting to enter the labor market.
Further prompting Mexican nationals to seek employment in the
United States is the fact that there is a significant disparity in
wage rates between this country and Mexico. In Mexicali and
Tijuana, both Mexican cities bordering the Southern District and
each with a population in excess of 400,000, the average daily wage
is about $3.40 per day. The minimum wage is even lower for workers
in the interior of Mexico. The average worker in Mexico, assuming
he can find work, earns in a day as much as he can make in only a
few hours in the United States.
In addition, it is estimated that the per capita income of the
poorest 40 percent of the Mexican population, the strata most
likely to leave their homeland in search of employment in the
United States, is less than $150 per year.
The manpower needs of the United States generated by World War
II resulted in many Mexicans being imported into this country and
becoming familiar with employment opportunities and practices in
the United States. See Diaz v. Kay-Dix
Ranch, 9 Cal. App. 3d
, 88 Cal. Rptr. 443 (1970).
The opportunities available to Mexican aliens have traditionally
been in agriculture. While still true in many parts of the United
States Southwest, in recent years, the pattern has changed, and
more and more illegal aliens are obtaining employment in the
service and manufacturing sectors of our economy. These aliens are
increasingly found in virtually all regions of the country
Page 422 U. S. 903
and in all segments of the economy. State Social Welfare Board,
Issue: Aliens in California, 12 (1973) [Hereinafter cited as
Aliens in California
The nature of the change in employment opportunities available
is demonstrated by one estimate that 250,000 illegal aliens are
employed in Los Angeles County, where agricultural opportunities
are known to be limited. Hearings on Illegal Aliens Before Subcom.
No. 1 of the House Comm. on the Judiciary, 92d Cong., 1st Sess.,
pt. 1, at 208 (1971) [Hereinafter cited as Hearings on Illegal
Other estimates of the impact of illegal aliens in California
suggest that, in 1971, when 595,000 Californians were unemployed
(7.4 percent of the State's labor force), there were between
200,000 and 300,000 illegal aliens employed in California earning
approximately $100 million in wages. Hearings on Illegal
Since the majority of Mexicans are unskilled or low skilled
workers, they tend to compete with Mexican-Americans, blacks,
Indians, and other minority groups who, due to the declining
percentage of jobs requiring low or no skills, are finding it
increasingly difficult to obtain gainful employment. Cramton
Illegal aliens compete for jobs with persons legally residing in
the United States who are unskilled and uneducated and who form
that very group which our society is trying to provide with a fair
share of America's prosperity.
In addition, illegal aliens tend to perpetuate poor economic
conditions by frustrating unionization, especially in such
occupations as farm work.
Illegal aliens pose a potential health hazard to the community,
since many seek work as nursemaids, food handlers, cooks,
housekeepers, waiters, dishwashers, and grocery workers.
Immigration and medical officials in
Page 422 U. S. 904
Los Angeles, for example, have discovered that the illegal alien
population in Los Angeles' barrio is infected with a high incidence
of typhoid, dysentery, tuberculosis, tapeworms, venereal disease
and hepatitis. L. A. Times, Sept. 16, 1973, pt. II, at 1.
In some states, illegal aliens abuse public assistance programs.
In some instances, entire families who entered the country
illegally have been admitted to the welfare rolls. Aliens in
at 35, 43.
Another aspect of the problem created by illegal aliens is that
employed aliens tend to send a substantial portion of their
earnings to relatives or friends in Mexico. This outflow of United
States dollars exacerbates our balance of payments problem to the
extent of $1 billion a year. Hearings on Illegal Aliens,
pt. 3 at 683.
The net effect of this silent invasion of illegal aliens from
Mexico is suffering by the aliens who are frequently victims of
extortion, violence and sharp practices, displacement of American
citizens and legally residing aliens from the labor market, and
irritation between two neighboring countries.
THE LAW ENFORCEMENT PROBLEM
Given that illegal aliens are a significant problem in American
life, especially for those minority groups who are described as
economically deprived, and that Congress has decreed that all but a
relatively few aliens are to be permanently excluded, then we must
analyze what law enforcement problems exist. In this regard, the
following findings of fact are made:
The illegal alien problem is one found primarily in the
Southwestern Region of the United States.
This problem along the Mexican-American border has existed for
some time, with the original responsibility for securing the
integrity of the border being assigned to
Page 422 U. S. 905
the U.S. Army, along with the Departments of Treasury and Labor,
who had about 20,000 men assigned to the border between
Brownsville, Texas, and San Diego, California, in 1920. National
Geographic Magazine, "Along Our Side of the Mexican Border." (July
Currently the burden of controlling the entry of aliens and
stemming the flow of illegal aliens along the Mexican-American
border is assigned to the INS. [Footnote 3/1
The border extends for almost 2,000 miles from the Gulf of
Mexico to the Pacific Coast.
Along this border, there were over 152 million legal entries at
authorized ports of entry during fiscal 1972, of which over 91
million were made by aliens. Over 39 million of the legal entries
were made at the three ports of entry in Southern California
(Calexico, San Ysidro and Tecate) of which over 24 million were
made by aliens. Immigration and Naturalization Service, 1972 Annual
Of these entries made by aliens, the large portion were made by
visitors with official permission to enter the country who had been
issued temporary "border passes" such as I-186 cards (issued to
residents of Mexico), which authorize the holder to travel within
an area no further than 25 miles from the border and for a period
of time not to exceed 72 hours. See
8 C.F.R. § 212.6.
These temporary border passes (I-186) are issued to simplify
procedures needed for entry, and the issuing process recognizes the
interrelationship of contiguous communities along both sides of the
border. Hearings on Illegal Aliens,
pt. 1, 192.
In fiscal 1973, approximately 208,000 I-186 cards were issued,
and it is estimated that over two million such
Page 422 U. S. 906
cards are currently in circulation. Hearings on Illegal
pt. 1, 173.
Within the INS, the U.S. Border Patrol, which was first
established in 1924, has the primary function of preventing the
illegal entry of aliens and the apprehension of those who have
entered illegally and those who smuggle these illegal entrants.
The Border Patrol has approximately 1,700 agents, who are well
trained law enforcement officers, and, of these, about 80 percent
are assigned along our southern border with Mexico.
A "deportable alien" is a person who has been found to be
deportable by an immigration judge, or who admits his deportability
upon questioning by official agents.
The number of deportable aliens apprehended by the Border Patrol
(which makes the great majority of apprehensions) nationally has
grown from 38,861 during fiscal 1963 to 498,123 in fiscal 1973; of
this number, 128,889 were found by Border Patrol agents working in
the Chula Vista sector, which includes 70 miles of the border in
San Diego County, and 23,125 were located by agents in the El
Centro sector, which includes the Imperial County of California and
75 miles of the Mexican-American border.
The Border Patrol agents have the power to apprehend illegal
aliens, since, by regulation, the Attorney General has designated
Border Patrol agents to be immigration officers, and authorized
them to exercise powers and duties as such officers [8 C.F.R. §
103.1(i)]; immigration officers by statute § 101(a)(17) of the
Immigration and Nationality Act of 1952, 66 Stat. 163; as amended
by the Act of October 3, 1973, 79 Stat. 911, 8 U.S.C. §
1101(a)(17), are empowered, without a warrant, to stop and
interrogate any alien or person believed to be an alien as to his
right to remain or to be in the United
Page 422 U. S. 907
States. See Au Yi Lau v. I.N.S.,
144 U.S.App.D.C. 147,
445 F.2d 217 (1971), cert. denied,
404 U.S. 864. . . .
Sec. 287(a)(3) of the 1952 Immigration Act provides authority
for an immigration officer within a reasonable distance from the
border of the United States to board and search any conveyance or
vehicle; "reasonable distance," as used in that section of the Act,
means within 100 air miles from any external boundary of the United
States, 8 C.F.R. § 287.1(b).
Immigration officers also are authorized to conduct inspection
of aliens seeking admission or readmission to, or the privilege of
passing through, the United States, and also are authorized and
empowered to board and search any vehicle or like conveyance in
which they believe aliens are being brought into the United States.
Sec. 235(a) of the 1952 Immigration Act, 8 U.S.C. § 1225(a).
The deployment of Border Patrol agents along the border is
intended to maximize the effectiveness of the limited number of
personnel, with the first line of defense being called the "line
watch." The line watch consists of agents being placed immediately
upon the physical boundary where experience has shown that large
numbers of illegal aliens can be detected attempting entry. A large
number of agents so assigned are primarily concerned with
responding to sensor alarms (electronic detection equipment) which
are located at strategic positions. These agents also respond to
citizen complaints concerning the suspected presence of deportable
In fiscal 1973, there were 175,511 deportable aliens apprehended
throughout the nation by agents assigned to the line watch, with
69,147 being apprehended in the Chula Vista sector and 5,908 in the
El Centro sector.
While the Border Patrol would like to apprehend all
Page 422 U. S. 908
deportable aliens right on the border by agents on the line
watch, inspections at regular points of entry are not infallible,
and illegal crossings at other than legal ports of entry are
numerous and recurring. The maintenance of continuous patrol over
the vast stretches of the border in Southern California is
physically impossible, since the approximately 145 miles of
boundary creates geographic barriers to effective patrol and
man-made devices such as fences and electronic devices are in,
large part, ineffective.
Increased manpower on line watch would not make that activity
appreciably more effective, as was demonstrated in 1969 during
"Operation Intercept," when many more agents were stationed
immediately on the border, and yet, the number of illegal aliens
apprehended by agents operating inland was not significantly
different from like periods when such additional manpower was not
located at the boundary.
Once the aliens negotiate their way through the port of entry
or, as is most common, walk across the border at a place other than
an official port of entry, they find transportation inland either
in public conveyances or private vehicles, with increasing numbers
being transported by professional smugglers. A few have been known
to walk some distance inland, and have been apprehended after
having walked as far north as Julian, California, which is over 60
miles from the border.
After crossing the line watch, some illegal aliens seek
employment in the Southern District, but the vast majority attempt
to proceed to Los Angeles County and points north.
Once the illegal alien gets settled in a big city far away from
the border, it becomes very difficult to apprehend him, and
therefore the Border Patrol attempts to contain the illegal entrant
within this district. Aliens in
Page 422 U. S. 909
at 7. With this objective in mind, they have
(pursuant to their statutory authority discussed above)
established, since at least 1927, strategically located traffic
inspection facilities, commonly referred to as checkpoints, on
highways and roads, for the purpose of questioning vehicle
occupants believed to be aliens as to their right to be, or to
remain, in the United States, and also to search such vehicles for
illegal aliens. Immigration and Naturalization Service Border
Patrol Handbook 9-1 (1972) [hereinafter cited as
The primary objective of the checkpoints is to intercept
vehicles or conveyances transporting illegal aliens, or nonresident
aliens admitted with temporary border passing cards (I-186), with
particular attention being paid to vehicles operated by smugglers
or transporters destined for inland cities in violation of 8 U.S.C.
The selection of the location of a checkpoint is determined by
factors relevant to the interdiction or interception of deportable
aliens who have succeeded in gaining entry in an unlawful manner or
are proceeding beyond the immediate border area in violation of
conditions of their admission as bordercrossers, 8 C.F.R. § 212.60.
The primary factors in selecting a checkpoint site are:
1. A location on a highway just beyond the confluence of two or
more roads from the border, in order to permit the checking of a
large volume of traffic with a minimum number of officers. This
also avoids the inconvenience of repeated checking of commuter or
urban traffic which would occur if the sites were operated on the
network of roads leading from and through the more populated areas
near the border.
2. Terrain and topography that restrict passage of vehicles
around the checkpoint, such as mountains, desert, and, as in the
case of the San Clemente checkpoint, the Camp Pendleton Marine
Page 422 U. S. 910
3. Safety factors: an unobstructed view of oncoming traffic, to
provide a safe distance for slowing and stopping; parking space off
the highway; power source to illuminate control signs and
inspection area, and bypass capability for vehicles not requiring
4. Due to the travel restrictions of the I-186 nonresident
bordercrosser to an area 25 miles from the border (unless issued
additional documentation) the checkpoints, as a general rule, are
located at a point beyond the 25 mile zone in order to control the
unlawful movement inland of such visitors.
Strategic sites that meet the foregoing enumerated criteria are
selected for "permanent checkpoints." These are sites equipped to
handle a large volume of traffic on what would be a 24-hour basis
except in case of manpower shortage, poor weather, or where traffic
becomes excessive causing a potential safety hazard.
Other traffic checkpoints, known as "temporary checkpoints" are
maintained on roads where traffic is less frequent. The placement
of these sites will be governed by the same safety factors as
involved in permanent site placement, and are usually located where
the terrain allows an element of surprise. Operations at these
temporary checkpoints are set up at irregular intervals and
intermittently so as to confuse the potential violator.
When the checkpoints, whether permanent or temporary, are in
operation, an officer standing at the "point" in full dress uniform
on the highway will view the decelerating oncoming vehicles and
their passengers, and will visually determine whether he has reason
to believe the occupants of the vehicle are aliens (i.e.,
"breaks the pattern" of usual traffic). If so, the vehicle will be
stopped (if the traffic at the checkpoint is heavy, as at
Page 422 U. S. 911
the San Clemente checkpoint, the vehicle will be actually
directed off the highway) for inquiries to be made by the agent. If
the agent does not have reason to believe that the vehicle
approaching the checkpoint is carrying aliens, he may exchange
salutations or merely wave the vehicle through the checkpoint.
If, after questioning the occupants, the agent then believes
that illegal aliens may be secreted in the vehicle (because of a
break in the "pattern" indicating the possibility of smuggling) he
will inspect the vehicle by giving a cursory visual inspection of
those areas of the vehicle not visible from the outside
trunk, interior portion of camper, etc.).
At the point of location of the sites now in regular use, few
aliens have reached the locale on foot, with 99 percent having
entered a vehicle of one type or another. Approximately 12 percent
of all apprehensions of deportable aliens throughout the nation are
made at checkpoints.
In the United States, during fiscal 1973, approximately 55,300
deportable aliens were apprehended by Border Patrol agents working
traffic checking operations. In the Chula Vista sector, the number
for that period was 21,232, while in the El Centro sector, the
total was 3,825. [Footnote 3/2
During fiscal 1973, a total of 4,975 of the above were visitors
apprehended at the checkpoints, and a majority of these were those
who were in violation of the terms of temporary border passes (Form
The placement of the checkpoints and their operations are
coordinated between the two sectors located in this
Page 422 U. S. 912
district and with Border Patrol activities to the east in
Arizona. In actual operation, the checkpoints, be they "permanent"
or "temporary," have the same basic accouterments. Typically, about
one-half mile to one mile south of the checkpoint is the first
notification that the checkpoint is ahead. The notice is in the
form of a black on yellow sign indicated "STOP AHEAD" which has
floodlights for nighttime illumination, Handbook
Next, about 200 yards from the checkpoint is another sign
cautioning the traffic to slow down or to be careful; this sign
usually has flashing yellow lights attached. For the fifty yards
directly south of the checkpoint there are placed traffic cones
evenly spaced along each side of the highway. The actual checkpoint
has a sign indicating to the traffic to stop, with official Border
Patrol vehicles parked on each side of the stop zone showing the
official Border Patrol emblem and/or the designation U.S. OFFICERS.
At this point, the agents assigned at the "point," in their
official uniform, conduct checking and inspection operations.
Beyond the checkpoint is usually a sign indicating "THANK YOU."
While a large number of apprehensions are made at the
checkpoints each year, as related above, the primary reason for
their operation is that they effectively deter large numbers of
aliens from illegally entering the country or violating the terms
of any temporary crossing card they may have, because they form an
effective obstacle and are located on all major routes north out of
the border region.
The deterrence aspect of these traffic checkpoint operations is
amply demonstrated by the fact that the illegal alien has to resort
to the employment of professional smugglers to provide
transportation around or through these checkpoints.
Some of these smuggling operations have developed
Page 422 U. S. 913
into sophisticated and involved operations with the following
general modus operandi:
1. Contact is made between the smuggler and the alien prior to
the latter's leaving Mexico.
2. The aliens then make entry on foot, with possibly the aid of
a "guide," or by use of temporary border passes. Then they enter
vehicles approximately 2 or 20 miles inland after having passed
through the Border Patrol's line watch activities.
3. To get through the traffic checkpoint, they might use a "drop
house," which acts as a staging area to keep the aliens awaiting
inclement weather, or any event that might cause the checkpoint to
close down temporarily. Or they may use a "decoy" vehicle, which is
a vehicle loaded with illegal aliens which it is anticipated will
be stopped at the checkpoint and would therefore occupy the agents
so that other vehicles could pass through without inspection. They
even use "scout cars" to probe those roads where temporary
checkpoints are maintained, so as to advise other vehicles whether
it is safe to proceed.
4. The "load" vehicles themselves can be of any type of
conveyance, and the methods used to secrete aliens inside them are
varied, and often show some originality. Unfortunately, sometimes
these are very dangerous to the aliens themselves. It has been
reported, for example, that it is not at all unusual for an alien
to die from asphyxiation while concealed in an automobile trunk or
a tank car.
5. The cost of the transportation provided to the aliens is
approximately $225 to $250 for each alien for the trip through the
checkpoint on to the Los Angeles area. Since smuggling operations
are almost exclusively "cash and carry" businesses and the average
income among Mexican nationals who may wish to seek residence
Page 422 U. S. 914
here illegally is quite small, this cost tends to act as a very
significant deterrent in and of itself. The checkpoints are the
major reason for such a high price, and if they were discontinued
for any length of time, it would be one more encouragement to
The deterrent impact of these checkpoints has been noted on
several occasions when they resumed operation unexpectedly and a
great number of aliens were apprehended.
The evidence presented before this court clearly established
that there is no reasonable or effective alternative method of
detection and apprehension available to the Border Patrol in the
absence of the checkpoints, for even a geometric increase in its
personnel or line watch would not leave any control over those
admitted as temporary visitors from Mexico.
Of the approximately half million illegal aliens apprehended in
fiscal 1973, virtually none were prosecuted, unless they presented
counterfeit or altered documents or aided in smuggling
This district has only 3 percent of the total length of land
borders, and yet fully 30 percent of all apprehensions of
deportable aliens made in the United States are made within this
The notation "INS" when used herein has reference to the
Immigration and Naturalization Service.
Apparently apprehensions other than those actually made at the
checkpoint are included in these figures, but they are a
representation of the total activity at these checkpoints and the
majority of apprehensions included therein are made at the
checkpoints [R.T. 274, 396].
MR. JUSTICE WHITE, with whom MR. JUSTICE BLACKMUN joins,
concurring in the judgment.*
Given Almeida-Sanchez v. United States, 413 U.
(1973), with which I disagreed but which is now
authoritative, the results reached in these cases were largely
foreordained. The Court purports to leave the question open, but it
seems to me, my Brother REHNQUIST
Page 422 U. S. 915
notwithstanding, that, under the Court's opinions, checkpoint
investigative stops, without search, will be difficult to justify
under the Fourth Amendment absent probable cause or reasonable
suspicion. In any event, the Court has thus dismantled major parts
of the apparatus by which the Nation has attempted to intercept
millions of aliens who enter and remain illegally in this
The entire system, however, has been notably unsuccessful in
deterring or stemming this heavy flow, and its costs, including
added burdens on the courts, have been substantial. Perhaps the
Judiciary should not strain to accommodate the requirements of the
Fourth Amendment to the needs of a system which, at best, can
demonstrate only minimal effectiveness as long as it is lawful for
business firms and others to employ aliens who are illegally in the
country. This problem, which ordinary law enforcement has not been
able to solve, essentially poses questions of national policy, and
is chiefly the business of Congress and the Executive Branch,
rather than the courts.
I concur in the judgment in these two cases.
* [This opinion applies also to No. 74-114, United States v.
p. 422 U. S.