Armslist.com isn't liable for the brutal murder of an Illinois woman shot to death by a man who used the online firearms marketplace to make an illegal gun purchase, a federal judge ruled this week.

The lawsuit was brought by the Brady Center to Prevent Gun Violence on behalf of the brother of Jitka Vesel, a 36-year-old immigrant shot and killed in 2011 by a Russian immigrant living in Canada. Gun-control advocates said the legal challenge was the first of its kind.

U.S. District Judge Charles Norgle of Illinois dismissed the wrongful death claim this week, concluding that Armslist can't be held responsible for the criminal conduct of its users.

"The Court finds that Defendant owes no duty to the general public to operate its website to control private individual users' sale of handguns," the judge wrote.

Attorneys for Armslist didn't respond to a request for comment.