Only if one of the statements made under oath is shown to be false.
Which is how Bill Clinton lost his law license for a while.
http://www.freerepublic.com/focus/f-news/1544869/posts
Did you read the article?
Under oath, several "witnesses" admitted they didn't see what happened, and either concocted their testimony based on hearsay from other people, and even to fit the autopsy report.
Just one of them:
Another witness had told the FBI after the shooting that he saw Wilson shoot Brown in the back, and then stand over his prone body to finish him off. But in his grand jury testimony, this witness, acknowledged that he had not seen that part of the shooting, and that what he told the FBI was "based on me being where I'm from and that can be the only assumption that I have."
There are many other examples. This wasn't an error in recollection. It was an outright fabrication.
The police should be prosecuting everyone of these people for lying under oath and/or filing a false police report. It shouldn't be tolerated.