Attorney General Jeff Sessions recently warned cities and towns that they could lose federal funding if they refuse to comply with federal immigration law—but if the ACLU has its way, complying in Massachusetts could actually be illegal.

The Massachusetts branch of the ACLU is bringing a case before the Supreme Judicial Court which would prevent federal immigration authorities, or ICE, from enlisting local enforcement to detain people without a warrant.

"The ACLU is arguing that in Massachusetts, law enforcement officers can't arrest somebody because somebody else asked them to, even if that someone is the federal government," explained Carol Rose, executive director of ACLU Massachusetts.

ICE can request local enforcement to detain a person for up to 48 hours after they have posted bail so their immigration status can be investigated. 

Some cities in the state have pushed back against this policy. Under the "Trust Act," a law passed in Boston in 2014, Boston Police can only comply with ICE requests if the person has committed a serious crime or if there is a court-ordered warrant.

Rose says compliance with ICE requests without a warrant violates protections in the state constitution against unlawful search and seizure.

"It violates due process. It violates equal protection under the law," she said.

Federal officials argue local enforcement should comply In the interest of comity, or cooperation between the local and federal governments. Rose disagreed.

"We believe in comity, but friends don't ask friends to violate the Constitution," Rose said.

Click on the audio player above to hear the entire interview with Carol Rose.