Immigration Detainers and Warrants

The County of San Mateo has an ordinance prohibiting cooperation with immigration authorities. The Sheriff’s Office follows the County ordinance and state law, and will not hold, detain, house, transfer, or otherwise facilitate the arrest of any person unless pursuant to a judicial warrant or otherwise required by federal or state statute, regulation, or court decision.

In compliance with the County ordinance, the Sheriff’s Office will publish quarterly reports on this website detailing the number of immigration detainer requests and warrants received from immigration authorities beginning Jan. 1, 2026.

* Information was not collected prior to March 2025  
** This is a warrant for the arrest of a person signed by a state or federal judge (not an immigration judge) and is legally required to be acted upon.