The U.S. Chamber of Commerce on Monday announced it would sue a group of activists who tried last week to impersonate their organization.

After the Yes Men staged a fake press conference at the National Press Club to "reveal" the Chamber supported cap-and-trade legislation, the Chamber has decided to sue the group for misappropriating its logo and violating a host of related copyrights.

“The Chamber is a strong proponent of free speech and encourages public debate on issues of the day,” said Steven Law, Chief Legal Officer and General Counsel of the U.S. Chamber of Commerce, in a statement Monday. “However, the law is clear that you can’t misappropriate others’ intellectual property for personal financial gain.”

The Yes Men began last week's hoax with a press release announcing the Chamber had made an "about face," and now supported pending climate change legislation in Congress. After a few reporters picked up on the release -- some of which accidentally reported it as true -- the activist group held a press conference to further make the case for why the Chamber now backed Democrats' climate change efforts.

But about 30 minutes into that press event, a Chamber spokesperson entered the room and ended the conference. The Chamber has since reiterated it does not, in fact, support climate change legislation, and the duped reporters have ultimately published their mea culpas.

On Monday, however, the Chamber of Commerce revealed it would also follow through with its original promise of legal action against the Yes Men. In their civil suit, filed in federal court on Monday, the Chamber argues the group is not comprised of "merry pranksters tweaking the establishment." Instead, explained the Chamber's legal adviser, the Yes Men "deliberately broke the law in order to further commercial interest in their books, movies, and other merchandise."

"Ironically and unfortunately, this lawsuit might even help in that regard, but these acts are nothing less than commercial identity theft masquerading as social activism and must be stopped," Law said in a statement.