It is important to know that US Constitutional protections apply to every person within US borders, including undocumented immigrants. The government has the power to decide who enters the country and under what circumstances, but immigrants who are here, even undocumented immigrants have many of the fundamental rights that US citizens enjoy.
Immigrants who are not here legally are subject to deportation and the Department of Homeland Security has the authority to question people about their right to be in the US. Most immigrants are entitled to a hearing that meets constitutional due process standards.
However, individuals who enter the United States under the Visa Waiver Program (VWP) as visitors for 90 days do not have a right to a hearing before an immigration judge if they become deportable by overstaying their 90 day status or by committing certain crimes. Immigrants who entered the US on the Visa Waiver program, if they come to the attention of the Department of Homeland Security, will be detained and removed without a hearing.
Some of the basic rights that you are entitled to as a resident of the US are:
The Right to Privacy
Unless police or government agents have a warrant they may not search your home without your consent. You can refuse to let them into to your home. If they say they have a warrant ask to see it. The warrant must tell in detail the places to be searched and the people or things to be seized.
New laws have expanded the government’s authority to conduct surveillance.
The Right to Remain Silent
You may refuse any question that is put to you. If you are driving a car, you must show them your license, registration and proof of insurance, but you do not have to consent to a search, although the police may have legal grounds to search your car anyway. If you are stopped on the street ask if you are free to go, if you are you can walk away.
For more information on your rights:
ACLU Know Your Rights Pamphlet (PDF)