How can an immigrant with expired B1 and B2 visas legally remain in the US?

Answer

Only if the person can qualify for asylee or refugee status.

The foreign national will likely be subject to deportation and will be barred from applying for reentry for the time specified under USCIS law.

United States Citizenship and Immigration Services, http://www.uscis.gov

Immigration and Customs Enforcement, http://www.ice.gov


Or if one is not married they can merry a US citizen and apply to permanent residency without leaving the country.