The number of Californians who have used marijuana probably jumped after Jan. 1, when the Golden State legalized recreational pot. California businesses, however, can refuse to hire anyone who fails a pre-employment drug test, provided businesses require all applicants to be tested.

Thirty states and the District of Columbia have legalized marijuana use in some form, and eight states and the District of Columbia permit recreational use. California has allowed the use of marijuana for medicinal purposes since 1996.

The widespread availability of recreational marijuana should prompt businesses and HR professionals to review their policies governing impairment, testing and drug-free workplaces.

Employees should be reminded, however, that they cannot possess, use, sell or work under the influence of marijuana or cannabis products such as edibles and infused oils on the job, even if it is for medical reasons. The California Supreme Court has ruled that the state’s Fair Employment and Housing Act does not provide protection on the job for current marijuana use, even if it is taken for medicinal purposes.

‘It Can’t be Fair’

“There is a lot of outcry that it can’t be fair,” said Robin Largent, an attorney with Carothers DiSante & Freudenberger in Sacramento. “If it’s legal to smoke it, how can you lose your job by smoking it?” Very easily, it turns out. The law specifies that it should not be interpreted as a license for employees to bring drugs to work and use or sell them there.

Further, legalizing recreational marijuana doesn’t void existing case law, said Jinouth Vasquez Santos, an attorney with Seyfarth Shaw in Los Angeles. The California Supreme Court held in 2008 that employers need not accommodate employees’ medical marijuana because the drug remains illegal under federal law.

California businesses can continue to require drug testing for prospective hires, even if they hold medical marijuana cards. And employers can refuse to hire anyone who fails a pre-employment test, including someone who smoked or ingested marijuana at home for a medical reason before the drug test.

[SHRM members-only HR Q&A: How does California law regarding medical marijuana use affect hiring and other workplace practices?]

Once job candidates become employees, however, drug testing is difficult to order and justify. The California Constitution’s right to privacy generally protects against random testing unless there’s a “reasonable suspicion” that the employee is under the influence. Reasonable suspicion might include decreased productivity and focus, bloodshot eyes, slurred speech or the odor of marijuana or alcohol on the person.

If an employee is so impaired that he or she cannot function effectively, management need not insist on a drug test; an employer could instead terminate the worker for failing to perform job duties, Largent said.

No Definitive Answers

Drug testing for some professions—such as pilots, nuclear power plant operators and public-transit drivers—may be mandated under federal law or federal contracts. California employers generally can require random drug testing for employees only if they can make a strong argument that drug testing would protect public safety, Vasquez Santos said.

But drug tests aren’t likely to provide definitive answers to whether a marijuana user is impaired. A California motorist with a blood-alcohol concentration level of 0.08 percent or higher is presumed to be driving under the influence of alcohol, but there’s no comparable level for THC, the ingredient in marijuana that causes intoxication.

“Studies haven’t been able to determine a correlation between THC levels and an inability to drive safely, according to both the National Highway Traffic Safety Administration and the American Automobile Association,” The San Francisco Chronicle recently reported.

Tolerance and impairment levels can vary depending on how long someone has been using marijuana, its concentration in a product and the delivery method chosen, said Christopher Olmsted, an attorney with Ogletree Deakins in San Diego.

State by State

Businesses with employees in California and other states that have legalized marijuana use face challenges because different case law applies in different jurisdictions. For example, a Connecticut judge ruled last summer that the state’s medical marijuana law protects authorized users, holding that they cannot be denied employment or be fired so long as they do not use it on the job and are not under its influence at work. A Rhode Island court reached the same conclusion last summer.

A Massachusetts employee with Crohn’s disease alleged disability discrimination after she was fired for failing a drug test. She used medical marijuana at home to reduce painful symptoms. The state’s highest court last year gave her a green light to pursue her discrimination case.

Different states are reaching different conclusions.