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 his or her 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 fail to abide by these conditions and maintain your nonimmigrant status, you become deportable.
It sounds harsh, but it's a crime for immigrants not to submit immediate notifications to U.S. Citizenship and Immigration Services (USCIS) of their changes of address. You've got ten days. Use the "Online 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 Section 237(a) of the Immigration and Nationality Act, or I.N.A. 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 label it a "crime of moral turpitude" or an "aggravated felony." You may simply be told that the crime is classified as, for example, a "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 laws 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 would not become a "public charge" -- that is, have to rely on need-based government assistance -- was an important part of proving that you were not inadmissible to the United States and get your 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.)
If you have a green card, your petitioner, and any other financial sponsor, are supposed to follow through with their promises to support you (and can also be asked to reimburse any agencies from which the immigrant received public assistance.)
If you are facing deportation due to one of the above mentioned reasons or for any other reason, consider speaking with an immigration attorney as soon as possible.