PASEDENA, Calif.—The 9th U.S. Circuit Court of Appeals has upheld a shipping port association’s and unions’ “one-strike rule” that eliminates applicants who fail a pre-employment drug screening from future employment.

The 2-1 ruling Wednesday in Santiago Lopez vs. Pacific Maritime Assn. et al. upheld a lower court’s grant of summary judgment dismissing his complaint, which alleged the denial of employment violated the Americans with Disabilities Act and the Fair Employment and Housing Act.

Mr. Lopez, who applied to be a longshoreman in 1997, was denied employment by Pacific Maritime when he tested positive for marijuana. Pacific Maritime, which represents the shipping lines, companies and terminal operators that run ports along the U.S. West Coast, has a “one-strike rule” that permanently disqualifies job applicants who fail the pre-employment drug test.

The applicants are notified seven days in advance of the drug screening, according to court documents.

Mr. Lopez, who in court documents said he was addicted to drugs at the time of his screening, reapplied in 2004 after undergoing treatment. Pacific Maritime rejected his subsequent application based on his drug test, which Mr. Lopez argued discriminated against him on the basis of his protected status as a rehabilitated drug addict.

The majority on the 9th Circuit panel disagreed, saying that the rule “eliminates all candidates who test positive for drug use, whether they test positive because of disabling drug use or because of an untimely decision to try drugs for the first time.”

The court also said Mr. Lopez’s disparate impact claim failed because Pacific Maritime’s drug screening procedure “does not necessarily screen out recovering drug addicts disproportionately.”

“We recognize that the one-strike rule imposes a harsh penalty on applicants who test positive for drug use,” Judge Susan P. Graber wrote for the majority, noting that many people could question the rule’s reasonableness after they rehabilitate themselves.

“But unreasonable rules do not necessarily violate the ADA or the FEHA,” she said. “Because the plaintiff failed to establish that the defendant intentionally discriminated against him on the basis of his protected status or that the one-strike rule disparately affects recovered drug addicts, we affirm the summary judgment in favor of the defendant.”

However, Circuit Judge Harry Pregerson, a member of the appeals court panel, dissented in part. While he said he agrees with the circuit court’s decision to grant summary judgment in favor of Pacific Maritime, the judge said he would have allowed Mr. Lopez’s case to proceed to determine whether the association’s lifetime hiring ban has an “adverse affect on recovering addicts.”