"Patriot Act" is the so-called "popular" title. The "official title" is "To deter and punish terrorist acts in the United States and around the world, to enhance law enforcement investigatory tools, and for other purposes."
If I had to guess, "and for other purposes" is basically a catch-all for anything not explicitly named.
It's still nothing like what an Australian law could be called. In Australia, it would be something like "Amendments to Homeland Security Act". Australia doesn't have the emotive (and misleading) titles the US does, because our legislative framework deters it.
Sounds quite reasonable to me. I do wish we had something in US law, as well. Every time a politician introduces a bill with a loaded name, it makes me want to retch.
If I had to guess, "and for other purposes" is basically a catch-all for anything not explicitly named.
http://thomas.loc.gov/cgi-bin/bdquery/z?d107:HR03162:@@@T