A federal judge in Manhattan has sharply narrowed one of the most closely watched criminal cases in the country, ruling that prosecutors cannot pursue the death penalty against Luigi Mangione in connection with the killing of UnitedHealthcare CEO Brian Thompson. Judge Margaret Garnett of the U.S. District Court for the Southern District of New York dismissed the murder count that exposed Mangione to capital punishment, while allowing stalking charges to remain in place.

The ruling is significant not only because of the profile of the alleged victim and the public attention surrounding the case, but also because it underscores the limits of federal charging authority in capital cases.

A federal judge in Manhattan has dealt a significant blow to the government’s strategy in the prosecution of Luigi Mangione, ruling that prosecutors cannot pursue the death penalty in the killing of UnitedHealthcare CEO Brian Thompson. The decision came by dismissing the federal murder count that opened the door to capital punishment, while allowing stalking charges to remain in place.

That distinction matters.