When legislation or regulation is what you rely on for privacy protection, your privacy protection relies on political consensus staying the same. When political consensus changes, your privacy can go away.
Witness the Department of Education’s proposed change to FERPA regulations—the Family Education Rights and Privacy Act—to make more data about students available to more people. The privacy protections that have applied until now are unlikely to withstand the Education Department’s belief that using data about students is more important.
To anyone who relied on FERPA for privacy protection: Oops!