What is deportation? It's commonly understood to mean when someone is sent out of the U.S. by the immigration authorities. The preferred technical term, however, is "removal."
Whatever word you use, there are many circumstances under which the immigration authorities can enforce someone's departure from the United States. Examples include officers catching immigrants attempting to cross the U.S. border and immediately returning them, removals of undocumented or criminal aliens who've been arrested and detained, and denials of cases in immigration court (perhaps after several appeals).
The agency on the front lines of immigration enforcement matters is Immigration and Customs Enforcement, or ICE. This agency would, for example, be the one to make arrests in the U.S., and to identify non-citizens who have been arrested for crimes and get them transferred into the immigration enforcement system after any prison time.
Everyday immigration matters, such as application processing are handled by U.S. Citizenship and Immigration Services, or USCIS. However, this agency can also send aliens into removal proceedings, most often when their applications for lawful permanent residence are unsuccessful and they have no other existing right to remain in the United States.
Customs and Border Protection is also a player, guarding not only the U.S. border but a broad swath of land within it, plus other points of entry such as air and seaports. CBP has the power to do "expedited" removals (with no hearing before a judge) as well as to refer people to removal proceedings with the EOIR (discussed next).
The final decisionmaker in many cases is the immigration court or Executive Office for Immigration Review (EOIR). This is where non-citizens who don't already have an order of removal on their record may defend themselves against removal and potentially establish a right to remain in the United States.
When most people think of an immigrant getting deported, they think of undocumented immigrants, often called illegal aliens. This mainly means people who either crossed the U.S. border illegally or stayed beyond their permitted time under the terms of a temporary (nonimmigrant) visa or after an entry on a visa waiver.
Indeed, many undocumented aliens enter and are removed from the U.S. each year. But they are not the only aliens who can be deported.
Any immigrant who violates the terms of his or her stay can be deported or removed from the United States. This might include a tourist who accepts a job (not allowed), or a student who fails to pursue a full-time course of study.
In addition, any immigrant who hasn't yet become a U.S. citizen, including a green-card holder (permanent resident) can be deported if he or she does something that's on the immigration law's list of grounds of deportability.
The grounds of deportability are found in § 237 of the Immigration and Nationality Act (I.N.A.) or 8 U.S.C. § 1227. For example, non-citizens can become deportable if they:
This is just a quick overview of these grounds. Do not rely on this list to analyze your case, but look at the law itself, linked to above, and consult with an experienced U.S. immigration attorney.
Also note that despite the seriousness of being accused of being deportable, some grounds can be overcome by requesting a waiver.
Non-citizens have the right to a lawyer, as well as other rights under the U.S. Constitution. The immigration authorities cannot simply deport someone without providing a chance to be heard.
Of course, the authorities often try to make the process go quickly, by asking the immigrant to sign something agreeing to depart without a hearing. In some cases, when the immigrant really is in the U.S. illegally with no defense to removal, leaving voluntarily can be the best way to go, because it avoids having an order of deportation on one's record.
But anyone who believes they might have a right to remain in the U.S. should insist on their right to a lawyer (which they will, unfortunately, have to pay for on their own) and to a hearing on the merits of their case.
A non-citizen who hasn't yet entered the U.S. does not have the same rights, and is subject to expedited removal. In other words, the person can simply be refused entry unless he or she has a legitimate fear of persecution if forced to return to his or her home country. In the latter case, the immigration officials must allow the person's asylum claim to be heard.
Immigration court proceedings are administrative, meaning they're less formal than ordinary court proceedings, and the usual rules of evidence don't apply. USCIS will be represented by its own attorney. The judge as well as both attorneys may ask questions of the immigrant, and either attorney may bring in witnesses to testify.
The hearing should last as long as is needed to present and hear all the evidence, though the Trump Administration has been putting intense pressure on judges to proceed quickly.
The judge may issue a decision at the end of the hearing, or later. If it's a negative decision, the judge will issue an order of removal, which becomes final as soon as the allotted time for appeal is over. Negative decisions can be appealed to the Board of Immigration Appeals (B.I.A.) by either party, and then through the federal court system.