Updated January 16, 2019
U.S. Immigration Laws for Aliens Arriving at the Border
In recent years, the migrant population arriving at the U.S.Mexico (Southern) border without legal immigration status
has shifted from being comprised predominantly of
Mexican adult economic migrants to being comprised
primarily of Central American adults, family units (adults
with at least one child under age 18), and unaccompanied
children, many of whom seek asylum in the United States.
How they are processed and what options they have for
legal admission and residing lawfully in the United States
depend on how they attempt to enter the United States,
whether they are children and/or arrive in families, what
country they originate from, and if they request asylum.
Aliens (foreign nationals) who wish to enter the United
States may request admission legally at a U.S. port of entry
or may attempt to enter the United States illegally between
ports of entry. The Department of Homeland Security
(DHS) has broad discretion to detain aliens, including
asylum seekers, during the pendency of removal
proceedings that determine whether they are admissible or
have other grounds to remain in the United States. Removal
proceedings involve either a formal hearing before an
immigration judge or a streamlined removal procedure (i.e.,
expedited removal) without hearings or significant review.
Arriving foreign nationals who seek asylum (described
below) may request it at a U.S. port of entry before an
admissions officer with the DHS Customs and Border
Protection (CBP) Office of Field Operations, or upon
apprehension between U.S. ports of entry before an agent
with CBP’s U.S. Border Patrol. All aliens requesting
asylum are entitled to an interview with an asylum officer
to assess the credibility of their asylum claims.
Illegal U.S. Entry
Aliens entering the United States illegally face two types of
penalties. First, the Immigration and Nationality Act (INA)
establishes civil penalties for persons who are in the United
States unlawfully (i.e., without legal status). These penalties
apply to aliens who entered the United States illegally as
well as those who entered legally but subsequently violated
the terms of their admission, typically by “overstaying”
their visa duration. Foreign nationals apprehended for such
civil immigration violations are generally subject to
removal (deportation) and placed in removal proceedings.
Second, the INA establishes criminal penalties for (1)
persons who are convicted of entering or attempting to
enter the United States illegally between ports of entry, (2)
eluding examination or inspection by immigration officers,
or (3) attempting to enter or obtaining entry to the United
States through fraud or willful misrepresentation (generally
classified as a misdemeanor). In addition, the INA provides
criminal penalties for persons who are convicted of
unlawfully re-entering the United States after being
removed from the country previously (generally classified
as a felony). Foreign nationals apprehended for criminal
immigration violations are subject to prosecution by the
Department of Justice (DOJ) in federal criminal courts.
Foreign nationals who attempt to enter the United States
without authorization often do so between ports of entry on
the U.S. border. If apprehended, they are processed and
detained briefly by CBP and either transferred to the
custody of another federal agency or placed directly into
removal proceedings. Procedurally, removal proceedings
occur after any criminal prosecution for illegal entry.
CBP typically refers apprehended aliens to DOJ for
criminal prosecution if they meet criminal enforcement
priorities (e.g., child trafficking, prior felony convictions,
multiple illegal entries). DOJ’s U.S. Marshals Service then
transports these individuals to DOJ criminal detention
facilities for pre-trial detention. After they have been
tried—and if convicted, served a criminal sentence—they
are transferred to DHS Immigration and Customs
Enforcement (ICE) custody and placed in immigration
detention. ICE, which represents the government in
removal hearings, then commences removal proceedings.
Because children are not permitted in DOJ criminal
detention with adults, prosecuting adults who cross the
border illegally with their children poses unique challenges.
Once DHS transfers an adult to DOJ custody, it generally
treats accompanying minor children as unaccompanied
alien children (UAC) and transfers them to the care and
custody of the Department of Health and Human Services
(HHS) Office of Refugee Resettlement (ORR) (see below).
However, a California federal court ruled that if DHS
separates families to enable the prosecution of adult illegal
entrants, DHS is required to reunite the families after
criminal proceedings conclude and any sentence is served.
Federal law contains distinct provisions for unaccompanied
alien children, defined as (1) lacking lawful immigration
status in the United States, (2) under age 18, and (3)
without a parent or legal guardian in the United States or
one available to provide care and physical custody.
UACs are not subject to expedited removal. Instead, a UAC
who immigration authorities determine to be subject to
removal is generally placed in formal removal proceedings.
DHS may permit a UAC to voluntarily return to his or her
country in lieu of removal proceedings, but only if the UAC
is a national or habitual resident of a contiguous country
(i.e., Mexico and Canada), and (1) has not been, or is not at
U.S. Immigration Laws for Aliens Arriving at the Border
risk in his or her country of being, a victim of human
trafficking; (2) does not have a credible fear of persecution
in his or her country; and (3) is capable of independently
withdrawing his or her application for U.S. admission. A
UAC from Mexico or Canada must be screened within 48
hours of apprehension to determine whether he or she can
If a UAC is not from a contiguous country or is from a
contiguous country but has a credible fear of persecution, or
CBP does not make a determination within the 48-hour
screening period, the UAC is to be placed in the custody of
ORR pending formal removal proceedings.
A child typically must be transferred to ORR within 72
hours after DHS determines he or she is a UAC. ORR must
then place the UAC “in the least restrictive setting that is in
the best interest of the child.” UACs are typically released
to sponsors, most of whom are parents or close relatives
already residing in the United States. In 2018, UACs spent
an average of 60 days in ORR custody.
Although UACs are not subject to expedited removal,
accompanied alien children, such as those arriving at the
border with family members, are generally treated the same
as non-citizen adults, and may face either expedited or
formal removal proceedings with the family unit.
Generally, DHS detains children and accompanying parents
in family residential centers for limited periods (typically
not exceeding 20 days) before releasing them pending their
Many aliens arriving at the Southern border seek asylum in
the United States. Asylum is a protection granted to foreign
nationals physically present within the United States or at
the U.S. border who meet the definition of a refugee. The
INA defines refugee as a person who is outside his or her
home country (a second country that is not the United
States) and is unable or unwilling to return because of
persecution, or a well-founded fear of persecution, on one
or more of five possible criteria: (1) race, (2) religion, (3)
nationality, (4) membership in a particular social group, or
(5) political opinion. Asylum is not numerically limited and
is granted on a case-by-case basis. Asylum can be requested
by foreign nationals who have legally entered the United
States and are not in removal proceedings (“affirmative”
asylum, not discussed below) or those who are in removal
proceedings and claim asylum as a defense to being
removed (“defensive” asylum).
Arriving aliens who are inadmissible, either because they
lack proper entry documents or because they attempt U.S.
entry through misrepresentation or false claims to U.S.
citizenship, are put into expedited removal. Aliens in
expedited removal who express a fear of persecution are to
be detained by ICE and given a credible fear interview with
an asylum officer from DHS’s U.S. Citizenship and
Immigration Services (USCIS) to determine if the asylum
claim has sufficient validity to merit a hearing before an
Credible fear means that there is “a significant possibility,”
taking into account the credibility of the statements made
by the alien in support of his or her claim and such other
facts as are known to the officer, that the alien could
establish eligibility for asylum. Those who receive a
favorable credible fear determination are placed into formal
removal proceedings and given a hearing before an
immigration judge, thereby placing an asylum seeker on the
defensive path to asylum. Those who receive an
unfavorable credible fear determination may request that an
immigration judge review the case. Aliens in expedited
removal who cannot demonstrate a credible fear are
Under the formal removal process, an immigration judge
from DOJ’s Executive Office for Immigration Review
(EOIR) determines whether an alien is removable. The
immigration judge may grant certain forms of relief (e.g.,
asylum, cancellation of removal), and removal decisions are
subject to administrative and judicial review.
Under streamlined removal procedures, which include
expedited removal and reinstatement of removal (i.e., when
DHS reinstates a removal order for a previously removed
alien), opportunities for relief and review are generally
limited. Under expedited removal, an alien who lacks
proper documentation or has committed fraud or willful
misrepresentation to gain admission into the United States
may be removed without any further hearings or review,
unless he or she indicates a fear of persecution in the home
country or an intention to apply for asylum. Two other
removal options, often referred to as “returns”—voluntary
departure and withdrawal of petition for admission—
require aliens to leave the United States promptly but
exempt them from certain penalties associated with other
types of removal.
Expedited removal can be applied to any alien who meets
the expedited removal inadmissibility criteria described
above, has not been admitted or paroled (i.e., given
temporary permission to enter or remain in the United
States despite being inadmissible), and cannot affirmatively
show continuous physical presence for the prior two years.
As a matter of policy, however, expedited removal to date
has been limited to persons apprehended within 100 miles
of the U.S. border and who have been present in the United
States for less than 14 days. Executive Order 13767, issued
on January 25, 2017, mandates that DHS expand expedited
removal to the full extent of the statute. That expansion has
not yet occurred.
If apprehended foreign nationals are found to be removable,
ICE and CBP share the responsibility for repatriating
them. CBP handles removals at the border for unauthorized
aliens from Mexico and Canada, and ICE handles all
removals from the U.S. interior and removals for all
unauthorized aliens from noncontiguous countries.
William A. Kandel, Analyst in Immigration Policy
Hillel R. Smith, Legislative Attorney
U.S. Immigration Laws for Aliens Arriving at the Border
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