District police say their ability to investigate terrorists would be undermined by legislation designed to prevent police from implementing a federal program that aims to take criminal illegal immigrants off the streets.

Police Chief Cathy Lanier wants to put in place some form of Secure Communities, a federal program through which local police send Immigration and Customs Enforcement the names of every arrestee to be checked against immigration databases.

But every member of the D.C. Council has backed a bill that would prohibit District police from sharing arrest information with ICE. The council introduced the legislation in May. Their maneuvering has become the latest in an ongoing battle of wills between the city's legislators and the Fenty administration.

On Monday Assistant Chief of Police Peter Newsham described the bill as "premature" during a public hearing.

"This preempts the police ability to implement the program in a way that's unique to D.C.," Newsham said. The District sits on law enforcement task forces, such as the Joint Terrorism Task Force, with ICE agents. "This would make it impossible to determine if a suspect is a legitimate terrorist threat."

A Fenty spokeswoman said the mayor "defers to the chief for law enforcement initiatives."

Every county in Virginia recently joined the program, as did Prince George's County. Federal authorities have set 2013 as a target for having every jurisdiction in the country online with Secure Communities. The District signed an agreement with the Justice Department in November to join Secure Communities. Newsham said officials want to limit the program so that misdemeanors and domestic violence cases would not be included in the arrest information sent to ICE. Council members and representatives of more than a dozen immigration organizations voiced concern that Secure Communities would spread fear and make some crime victims less likely to provide information to police. "Our goal is to use biometric information sharing to prevent criminal aliens from being released back into the community," an ICE spokeswoman said. "We will continue to work with D.C. to address any concerns they might have about the program."