Immigrants living in the United States may be subject to removal proceedings, even if they are legal permanent residents. If you've received a deportation notice, the federal agency that handles immigration allows you to plead your case at a deportation hearing; a letter of support can supply strong evidence that you should be allowed to remain.
The federal law governing immigration, the McCarran Walter Act, dates to 1952; removal proceedings are also governed by this and the Illegal Immigration Reform and Immigrant Responsibility Act of 1996. The law currently sets multiple reasons for removal; these include a fraudulent visa application, an expired visa, various criminal offenses, unlawful voting, and failure to report a change of address when required. The USCIS website provides the complete text of the law, including sections on deportable aliens and removal proceedings.
When the US Citizenship and Immigration Service begins deportation proceedings, it notifies the individual with a charging document and a Notice of Appear. The charging document lists the reason for the pending removal; the Notice to Appear sets a public hearing on the matter. At the hearing, an immigration judge hears from a government attorney as well as the “defendant,” who may also be represented by an attorney. At the hearing, the judge listens to arguments from both sides and may also consider any written evidence the defense can bring, including letters of support from family members, work colleagues, employers, acquaintances or public officials.
A letter of support may help persuade the judge that the government should cancel, or at least delay, removal. The letter must present a legal foundation for the plea; it must cite a specific exception in immigration law that would argue against deportation. For example, a legal permanent resident who has been in the US for at least five years, or who has resided in the US for at least seven years under any status, and has not been convicted of any aggravated felony, can benefit from an exception based on these circumstances.
Without legal foundation, a letter in support of the defendant must make the case that removal would mean severe and undue hardship for family members who are citizens or legal residents in the United States. The letter should also provide evidence that the defendant is of good moral character, is able to support himself, and has never been involved in drug trafficking or firearms violations. The law also makes an exception for victims of domestic violence and their children. These extenuating circumstances will sometimes result in a “parole.” This means the USCIS cancels removal proceedings and allows the defendant to apply for an adjustment of status to lawful permanent resident.