A Wayne County sheriff is urging his staff to deny detainer requests by U.S. Immigration and Customs Enforcement.

According to an April 28 memo obtained by The Detroit News, Wayne County Sheriff Benny Napoleon ordered staffers to deny any ICE requests to turn over immigrant inmates without an order signed by a judge or magistrate.

More from the sheriff's memo:

“Recent court decisions have raised Constitutional concerns regarding the enforcement of Immigration Detainer — Notice of Action (IDNA). As such, effective immediately members of the Wayne County Sheriff’s Office shall not honor any IDNAs from (ICE), unless one of the following conditions is met: Written Judicial Determination of Probable Cause ... or a warrant from a Judicial Officer. Unless one of the two above conditions are met, the Wayne County Sheriff’s Office will not honor IDNAs, and members shall not extend custody of an individual (inmate) beyond the original booking and detention periods of the original charge and bail."

Detainer requests are usually issued by ICE when agents think an inmate might be violating immigration laws. Agents ask local police to hold accused inmates, to allow ICE to take them into federal custody.

Detroit ICE spokesman Khaalid Walls says he's delaying any comments about the memo "until we've had a chance to fully review the (Wayne County) policy."