Nick Carter is back for a sex lawsuit, and witnesses say the accuser is suffering

Nick Carter Provides support for sexual battery lawsuit against him… says he has dozens of witnesses claiming his accuser is full of BS.

According to new legal documents, obtained by TMZ, the Backstreet Boys member says he has 12 people who testified that the alleged victim’s version of events could not be true.

TMZ broke the story… Nick has been sued by a woman named Shannon Rothwho filed a lawsuit in December claiming he sexually assaulted her after a concert way back in 2001 when she was underage.

But Nick says not so fast… He claims to have 12 witnesses from the party – fans, security personnel and a talent manager – who say the accuser’s story is “indeed impossible”.

Remember… Ruth, who says she’s autistic and has cerebral palsy, claims she lined up to get Nick’s autograph after the show, when he invited her back onto his tour bus, bound her with alcohol and forced her to perform anywhere they had sex on him.

But, Nick says dozens of his witnesses testified that it would have been impossible for him to interact with the alleged victim after the concert… They say there was no autograph line and fans had no access to the tour bus staging area.

What’s more, Nick says one of Ruth’s best friends at the time witnessed Ruth lying about being autistic and having cerebral palsy…and she couldn’t even believe Ruth was at the concert.

In the documents, Nick claims another witness testified that he was on calls where Ruth’s name was mentioned as part of a plot to blackmail Nick… an alleged money grab he mentioned earlier in his suit against Ruth.