Evidence of Patriot Act Abuses

One of the talking points that I've heard from people that support the Patriot Act, including adn most often politicians, is that there is no evidence of abuse taking place. It seems to matter not to these people that the Patriot Act is designed is such a way so as to suppress evidence of actual abuses, but this article provides a very real example:

"the statute has the practical effect of silencing those who have the most intimate knowledge of the statute's effect and a strong interest in advocating against the federal government's broad investigative powers." It creates a situation where "the very people who might have information regarding investigative abuses and overreaching are peremptorily prevented from sharing that information with the public."