The U.S. Supreme Court unanimously ruled Jan. 19 that the background checks NASA has conducted on workers are constitutional.

Twenty-eight workers at the Jet Propulsion Lab in Pasadena, Calif — engineers and scientists who do not handle secret information — had filed suit to block the checks, which NASA began conducting on contract workers after the 2001 terrorist attacks. The workers, who said the investigations were an invasion of privacy, won an appeal blocking them.

In a 40-page decision written by Justice Samuel Alito, the court ruled that open-ended questions about drug treatment “are reasonable, employment-related inquiries that further the government’s interests in managing its internal operations.”

Alito rejected the workers’ invasion-of-privacy claims, saying they were based on a misreading of previous cases.

The government “has an interest in conducting basic background checks in order to ensure the security of its facilities and to employ a competent, reliable workforce to carry out the people’s business,” Alito wrote. “The interest is not diminished by the fact that respondents are contract workers.”

NASA civil servants have been subject to background checks since 1953. In 2005, a presidential order extended the checks to contractors.

But the 9th U.S. Circuit Court of Appeals blocked the checks before the inquiries began in 2007, barring NASA from asking “open-ended” questions — the same questions the Supreme Court said are permissible.

“The government, recognizing that illegal drug use is both a criminal and medical issue, seeks to separate out those drug users who are taking steps to address and overcome their problems,” Alito wrote. “Thus, it uses responses to the drug-treatment question as a mitigating factor in its contractor credentialing decisions. The court rejects the argument that the government has a constitutional burden to demonstrate that its employment background questions are ‘necessary’ or the least restrictive means of furthering its interests.”

Of the 74,000 contractors who applied for ID badges over the last five years, 128 were rejected based on their replies to NASA’s questionnaires, according to arguments in the case. But no contractors were rejected for acknowledging treatment for drug use.

Robert Bohn, a lawyer with McKenna Long and Aldridge in Los Angeles who deals with national security clearances, said private workers should expect greater scrutiny since the 2001 terrorist attacks.

“I don’t think it’s a giant surprise,” Bohn said of the Supreme Court’s decision. “I think it’s noteworthy.”

Four of five employers use background checks similar to the ones debated in the NASA case, according to arguments in the case.

The case drew attention throughout the government. Contractors at agencies such as the Forest Service, the Department of Health and Human Services and the Department of Education contacted the NASA workers to support them during the case.