Companies can just say no to former drug addicts--at least sometimes--the Supreme Court ruled recently. The decision was notable because former addicts are explicitly protected under the 1990 Americans with Disabilities Act (though current users are not). But, the court found, it's now okay to refuse to rehire a recovering addict if he or she was let go for violating company policies.

The distinction is subtle but important, experts say.

The case involved Joel Hernandez, a technician at a Tucson missile plant who left his job in 1991 when he tested positive for cocaine use, a breach of company policy. Three years later, after he'd completed rehab and joined a church, Hernandez asked for his job back, attaching a letter from an Alcoholics Anonymous counselor with his resume. The plant, now owned by Raytheon, refused to take him back--citing a blanket policy against rehiring anyone previously terminated for violating the company code of conduct.

Attached to the resume: a letter from an alcoholics anonymous counselor.

Hernandez sued, claiming he had been discriminated against as a former addict. Raytheon countered that its ban on rule breakers applies equally to all applicants, whether or not they are former drug addicts. In court, the person who reviewed Hernandez's application at the plant testified that she didn't know that he was a former addict. She made her decision against rehiring based on his personnel file, which simply noted that he had been fired for violating an unspecified policy. In a 7-0 decision in December, the court backed Raytheon.

What protected the company was the consistency of its HR practices, says Paul Sarvadi, CEO of the HR outsourcing giant Administaff. Hernandez's file contained just enough information to give the hiring manager a heads up, without including the detail that could be construed as bias under the ADA. Still, Sally Simmons, a Tucson attorney who practices employment law, says companies should be careful. She notes that the court didn't discuss a key provision of the ADA, which states that even a policy applied to former addicts and nonaddicts alike may still be illegal if, over time, former addicts can show that it affects them disproportionately. In other words, if Raytheon's supposedly neutral rule is found to single out only former addicts, Hernandez may yet have a viable case.