There are several reasons for the U.S. immigration authorities to deport an immigrant—that is, send the person back to his or her country of origin. One of the most obvious is that the immigrant simply did not have a right to be in the United States to begin with, having crossed the border or otherwise entered illegally, or stayed beyond the departure date required by a visa.
However, even people who have a temporary or permanent right to remain in the United States, such as with an unexpired visa or a green card, can be removed or deported. Here are some of the common causes of deportation.
If you are in the U.S. as a nonimmigrant (most likely with a visa), various conditions apply to your stay. For example, if you're a tourist, you're not allowed to work. If you are a J-1 exchange student, you're not allowed to quit your program and take a job.
If you fail to abide by these conditions and maintain your nonimmigrant status, you become deportable.
It sounds harsh, but it's a crime for immigrants (green card holders) not to submit immediate notifications to U.S. Citizenship and Immigration Services (USCIS) of their changes of address. Even nonimmigrants (on temporary visas with stays long enough that they're actually living in the U.S.) are expected to send in such notification.
You've got ten days. Use the Change of Address form on the USCIS website.
A number of crimes—though not all—can result in an immigrant's becoming deportable from the United States. The full list is at § 237(a) of the Immigration and Nationality Act, or I.N.A (8 U.S.C. § 1227.).
For example, crimes that can get a green card holder or nonimmigrant deported include alien smuggling, document fraud, domestic violence, crimes of "moral turpitude," drug or controlled substance offenses firearms trafficking, money laundering, fraud, espionage, sabotage, terrorism, and of course the classic serious crimes such as rape, murder, and any other "aggravated felonies."
Be aware that, if you are convicted of a crime, the court is not likely to directly label it a "crime of moral turpitude" or an "aggravated felony." You might simply be told that the crime is classified as, for example, a "felony" or even a lesser "misdemeanor" in your state. However, the immigration authorities will make their own judgment about how the crime is classified for immigration law purposes, with the result that certain misdemeanors can, in fact, make you deportable.
Someone who violates the immigration law by, for example, participating in a fraudulent marriage or helping smuggle other aliens into the United States, may be found deportable.
Anyone who has received a green card knows that proving that you will not become a "public charge"— that is, have to rely on need-based government assistance—was an important part of showing that you were not inadmissible to the United States and deserved a green card.
The immigration laws follow this up with the statement that, "Any alien who, within five years after the date of entry; has become a public charge from causes not affirmatively shown to have arisen since entry is deportable." (See Section 237(a)(5) of the I.N.A., or 8 U.S.C. Section 1227(a).)
If you have a green card, your U.S. petitioner, and any other financial sponsor, are supposed to follow through with their promises to support you. They can also be asked to reimburse any agencies from which the immigrant received public assistance. If that doesn't work out, you might find yourself in deportation proceedings, or unable to reenter the U.S. after foreign travel.
If you are facing deportation (removal) due to one of the above-mentioned reasons or for any other reason, consider speaking with an immigration attorney as soon as possible.