Banned from the public library?

http://www.azcentral.com/news/articles/0706phxlibrary06.html

14 patrons were banned from using the computers at the Phoenix Public Library because they used the computers to access pornography. Pornography is not constitutionally protected free speech, so the library has no reason to tolerate such use of their computers. However, because of this, the library is keeping a record of all sites uploaded or downloaded by their patrons for thirty days. The intention is that they would only be available on court order; however, there seems to be a potential privacy issue here. The library will also use Internet filters and hire more staff to help prevent something like this from happening again.