The US Government (specifically, the Department of Homeland Security.)
Important excerpt from the article (emphasis mine):
So, in other words, the DHS can seize your laptop if you're crossing the border, for no better reason than "we felt like it", hold it indefinitely, and give any information contained therein (or on a Blackberry, or iPhone, or PocketPC) to anyone they choose.
Federal agents may take a traveler's laptop or other electronic device to an off-site location for an unspecified period of time without any suspicion of wrongdoing, as part of border search policies the Department of Homeland Security recently disclosed.
Also, officials may share copies of the laptop's contents with other agencies and private entities for language translation, data decryption or other reasons, according to the policies, dated July 16 and issued by two DHS agencies, U.S. Customs and Border Protection and U.S. Immigration and Customs Enforcement.
If it weren't for the fact that they're rewriting the laws to allow it, I'm fairly certain this would qualify as "unlawful search and seizure... but when has something like the Constitution stood in the way of the Bush administration, eh?
So, our first Asshat of the Day (doubtless destined to recover the honour many more times) - the Department of Homeland Security.