Examples, please...
"In Platteville, peace activist Frank Van Den Bosch was arrested for holding up a sign that was critical of the president. The sign's "dangerous" message, "FUGW," was incomprehensible to children and, no doubt, to many adults. Yet, it was still determined sufficiently unsettling to the royal procession that Van Den Bosch was slapped with a disorderly conduct ticket."
"Wolf and hundreds of other Wisconsinites and Minnesotans who sought to express dissents were videotaped by authorities, told they could not make noise, ordered not to display certain signs and forced to stand out of eyesight of Bush and his entourage. Again and again, they were told that if they expressed themselves in ways that were entirely protected by the First Amendment to the Constitution of the United States, they would be "subject to arrest."
That's just from this article. But this is not a new policy.