Many observers were shocked and saddened when Brandon Coats, a quadriplegic who is authorized to use medical marijuana under Colorado state law, was fired from his job with Dish Network in 2010 after a positive drug test. Dish failed to make an exception for Coats, who used marijuana while off duty to control his seizures, and the company insisted on his being fired, leaving Coats no choice but to challenge this issue in court.

Specifically, Coats claimed that his conduct should have been permitted under the state's Lawful Off-Duty Activities Statute, which makes it an unfair and discriminatory labor practice to discharge an employee based on the employee's "lawful," away-from-work activities. But the trial court, followed by the Court of Appeals and now the Colorado Supreme Court, have all ruled that the statute only protects conduct that is legal under both state and federal law — and therefore offers no job protection to Coats.

"Therefore, employees who engage in an activity, such as medical marijuana use, that is permitted by state law but unlawful under federal law are not protected by the statute," Justice Allison H. Eid wrote in the opinion.

This case highlights one of the most pressing issues that needs to be addressed in the states that have legalized medical cannabis use — and the states that have adopted full legalization for all adults, as well. Although employees are protected from arrest and prosecution under state law by these various laws, they remain vulnerable to employment discrimination in almost all states.

Simply put, if an employer wants to insist on what they frequently call a "drug-free workplace," they are legally permitted to do that — regardless of the unfairness this policy may cause, because we must note that they do not apply those same standards to off-job alcohol consumption or the use of prescription drugs.

Most Americans would strongly support the right of an employer to fire anyone who comes to work in an impaired condition. But smoking marijuana leaves one mildly impaired only for about an hour and a half; Certainly smoking marijuana in the evening, or on the weekend, would have no impact on the employee who comes to work the following day.

What we really need is for employers in these legalized states to become responsible corporate citizens and to do the right thing: Stop penalizing employees, absent a showing of impairment on the job. But absent that voluntary shift in policy, the obligation is now on those of us who favor marijuana legalization to go back to the state legislatures in states that have legalized cannabis, either for medical use or for all adults, and enact appropriate job protections for those who use marijuana legally under state law.

Before being allowed to fire an employee who tests positive for THC, the employer must be required to demonstrate on-the-job impairment. Just as we do not permit someone to be fired for reason of their gender, religion or race, neither should we permit an employee to be fired simply because they elect to use marijuana legally under state law, without a showing of actual on-job impairment.

Otherwise we are requiring many medical-use patients to choose between relieving their pain and suffering and keeping their employment. And we are allowing employers to fire good, hard-working, loyal employees for off-the-job activities that are totally unrelated to their job performance.

And that is simply unfair, and it cannot be allowed to stand. So let's get to work and fix this problem.

Keith Stroup is an attorney, author of "It's NORML to Smoke Pot: The 40-year Fight for Marijuana Smokers' Rights" and founder of the National Organization for the Reform of Marijuana Laws, where he serves as legal counsel.