Federal prosecutors are suing a nonprofit group that wants to open the nation’s first supervised injection facility in Philadelphia, NPR reports.

The nonprofit group, Safehouse, planned to open a facility where people could inject drugs under medical supervision, in an effort to prevent overdoses.

The Philadelphia District Attorney has said he would not prosecute anyone operating such a facility, or those who use drugs there. This is the first time the federal government has intervened in the issue of supervised injection sites, the article notes. About a dozen other cities are also considering opening supervised injection sites.