"If an alien who is unlawfully present in the United States is convicted of a violation or convicted of a violation of state of local law, on discharge from imprisonment or assessment of any fine that is imposed, the alien shall be transferred immediately to the custody of the United States Immigration and Customs Enforcement or the United States Customs and Border Protection."
Federal law states the burden of proof falls on the alien for documents of legal immigration. How can a transfer of custody take place if you aren't allowed to ask for documents?
If the concern is for U.S. citizen rights, we have the 14th Amendment of the U.S. Constitution. The first section on citizenship rights reads:
"All persons born or naturalized in the United States, and subject to the
jurisdiction
thereof, are citizens of the United States and of the State wherein they reside. No state shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States; nor shall any State
deprive
any person of life, liberty, or property, without
due process
of law; nor deny to any person within its
jurisdiction
the equal protection of the laws.
The key phrase is "without
due process
of law." It is not a violation when probable cause, reasonable suspicion, and a legal arrest or detention exist to require a U.S. citizen to identify him or herself.