"Background checks are a standard way of doing business," Acting Solicitor General Neal Katyal said before the Supreme Court, according to a transcript released today. "The Government has required them for all civil service employees since 1953 and for contractors since 2005."

Justices Sonia Sotomayor and Samuel Alito probed the boundaries of the background checks, inquiring whether employees could be asked questions about such topics as their genetic make-up, sexual practices or medical conditions.

The JPL scientists argue that their work is low-risk, unclassified and does not require security clearance. In their lawsuit, stemming from a 2004 NASA rule, the scientists claim that the background investigations violate their rights under the First, Fourth and Fifth Amendments and the Federal Privacy Act.

The plaintiffs said in an earlier statement that they do not challenge the government's right to perform comprehensive background checks when necessary, but that it is not necessary for unclassified work that does not threaten national security.