CHICAGO – The U.S. Supreme Court on Monday delivered another blow to a 50-year-old anti-eavesdropping law in Illinois, choosing to let stand a lower court finding that key parts of the hotly debated law run counter to constitutional protections of free speech.

In that critical lower-court ruling in May, the 7th U.S. Circuit Court of Appeals found that the law – one of the toughest of its kind in the country – violates the First Amendment when used against those who record police officers doing their jobs in public.

Civil libertarians say the ability to record helps guard against police abuse. The law’s proponents, however, say it protects the privacy rights of officers and civilians, as well as ensures that those wielding recording devices don’t interfere with urgent police work.