Brandon Mayfield is a 38-year old American citizen. He is a former Army office with an honorable discharge and a practicing lawyer. Prior to his arrest based on the Patriot Act, he had never been arrested. Mayfield is Muslim.
In 2004, the FBI began surveillance on Mayfield and his family. The FBI followed them to work, school, the Mosque they attend, and other places. The FBI also placed electronic surveillance devices in their home.
The FBI contends that it took this action because it believer, based on a partial match fingerprint, that Mayfield may have been involved in the terrorists bombings in Madrid, Spain on March 11, 2004. But, the Spanish National Police did not share this conclusion. Regardless, the FBI arrested Mayfield and imprisoned him for two weeks. Mayfield was released when the Spanish National Police informed the FBI that the fingerprint actually belonged to an Algerian, Ouhane Daoud.
While the facts of Mayfield's arrest are interesting, they are not directly relevant to the court opinion because he brought a facial challenge to the two provisions, not an as-applied challenge. In other words, the focus of his claim is that the two provisions at issue always violate the Fourth Amendment, not just in his particular case.
Specifically, Mayfield challenged the way in which the Patriot Act amended FISA. Before the Patriot Act, the government could only get a search warrant from a FISA court if the "primary purpose" was related to gathering national security intelligence. The Patriot Act lowered the standard to allow FISA warrants when merely a "significant purpose" of the warrant was related to national security intelligence. Thus, the Patriot Act allowed the government to obtain FISA court warrants when the primary purpose was to gather evidence related to domestic criminal activity. This lower standard violates the Fourth Amendment's probable cause requirement.
As the Mayfield court stated:
Since the adoption of the Bill of Rights in 1791, the government has been prohibited from gathering evidence for use in a prosecution against an American citizen in a courtroom unless the government could prove the existence of probable cause that a crime has been committed. The hard won legislative compromise previously embodied in FISA reduced the probable cause requirement only for national security intelligence gathering. The Patriot Act effectively eliminates that compromise by allowing the Executive Branch to bypass the Fourth Amendment in gathering evidence for a criminal prosecution.
As a remedy to Mayfield, the court not only found this change in the law unconstitutional, it ruled that the "Executive Branch must destroy or otherwise eliminate" the materials in its files that were the fruits of the unconstitutional search.
In short, the privacy implications of this case relate to the government's ability to conduct surveillance and create and retain databases of information on American citizens using FISA without having to prove probable cause, even when the primary purpose of the surveillance is not related to national security. While this decision is a victory for privacy interests, it is not the last word. Most likely, the government will appeal. Nonetheless, six year after passing the Uniting and Strengthening America by Providing Appropriate Tools Required to Intercept and Obstruct Terrorists Act (aka USA Patriot Act), privacy concerns seem to be getting some traction in the courts.