The American Civil Liberties Union of Minnesota sent letters to every county sheriff in Minnesota on Wednesday urging them to stop holding immigration detainees for the federal Immigration and Customs Enforcement (ICE).

Known as "ICE holds," the practice identifies prisoners in custody who may have an issue with immigration and allows the jail to hold prisoners for an additional 48 hours past when they might otherwise be released.

In its letter, the Minnesota ACLU said recent court decisions have established that the ICE holds are merely a request and not a command; and that sheriffs have no legal obligation to honor the request.

The organization also suggests that complying with the requests forces county taxpayers to incur unnecessary per diem costs for housing detainees who might otherwise be released.

"The growing spate of federal court decisions should serve as an important warning for local law enforcement throughout Minnesota," staff attorney Ian Bratlie said in a statement with the letter.

ICE holds add up

In its letter, the ACLU cited data from the Syracuse University-based TRAC program showing how widespread the practice is in Minnesota. Between October 2011 and August 2013, ICE issued more than 5,300 detainers to Minnesota jails. Almost every county jail in Minnesota was asked to hold prisoners past their release date, TRAC data show.

In data obtained through the state's Data Practices Act, the local ACLU found that Hennepin County, the state's most populous, spent more than $192,000 between 2010 and the end 2011 on keeping 1,272 ICE detainees. Blue Earth County in southeastern Minnesota spent more than $4,200 from September 2009 to September 2011 on 20 ICE detainees, according to the ACLU's review.

According to the TRAC data, 54 percent of immigration detainers in Minnesota are lodged against people with no criminal record and involve people who would typically be released from pretrial detention.

James Franklin, executive director of the Minnesota Sheriffs' Association, said he was unaware of the ACLU's most recent letter but said ICE holds have been a long-standing issue between law enforcement and immigration advocates.

Franklin said each sheriff will have to review this letter and consult with their respective legal counsel. Franklin said he was also disappointed that the ACLU issued a news release about the letter before sheriffs would get a chance to review it. "If the ACLU attempt is to 'educate and establish a dialogue' with law enforcement on this issue, it would appear that mission has failed," he said.

Requests for comment from Hennepin and Blue Earth counties were not returned.

ICE defends detainers

ICE said the detainers are critical for ICE to be able to identify and ultimately remove criminal aliens who are currently in federal, state or local custody.

A statement from the agency said it "will continue to work cooperatively with law enforcement partners throughout Minnesota as the agency seeks to enforce its priorities by identifying and removing convicted criminals and others who are public safety threats."

The ICE holds are different from contracts ICE has with some county jails to hold people being processed through the immigration court system. ICE detains some people while their cases are being processed or if they are about to be deported. It has contracts with five Minnesota county jails for those detainees.

Those use of those contracts recently came under scrutiny in Sherburne County when a sex offender housed in the jail for the Minnesota Department of Corrections was charged with sexually assaulting an ICE detainee.

The ACLU said in its letter that over 50 jurisdictions have abandoned the practice of automatically honoring ICE hold requests. Sheriffs in Los Angeles, Chicago and San Francisco now refuse to honor immigration detainers when the subjects have minor criminal records.

Mark Brunswick • 612-673-4434