As covered by the New York Times:

"[M]arijuana’s recent strides toward the legal and cultural mainstream are running aground at the office.  Even as 23 states allow medical or recreational marijuana, employment experts say that most businesses are keeping their drug-free policies.  The result is a clash between a culture that increasingly accepts marijuana and companies that will fire employees who use it." ( link)

During July New York passed a medical marijuana law permitting New Yorkers suffering from a narrow list of conditions to obtain marijuana for medical treatment.

This development in turn sets up a future series of conflicts between employers and at least some state and/or local disability discrimination laws, which may require reasonable accommodations for people with disabilities -- the people many of the medical marijuana laws are targeted to assist.

New York is no exception.  Indeed, it appears ripe for this conflict because of the state law's definition of those permitted to use medical marijuana as "disabled" within the meaning of New York disability discrimination law:

"The New York law specifically classifies individuals prescribed medical marijuana as 'disabled.'  Accordingly, employers may need to provide reasonable accommodation for medical marijuana users.  While courts have not yet addressed the issue of what constitutes a 'reasonable accommodation' for medical marijuana use, one suggestion is relaxing an employer's drug policy to permit the employee's medical marijuana use. Whether or not such 'accommodation' is reasonable will depend on the employee's specific job.  While it is low cost to the employer, if the side effects of marijuana have a negative impact on the employee's job, as could be the case of truck drivers or machine operators, such accommodation may not be reasonable."  ( link)

Advocates for reasonable accommodations regarding medical marijuana use with respect to drug policies are in no small part assisted by increasing voices in support of the positive medical effects of marijuana -including Dr. Sanja Gupta. 

Dr. Gupta recently noted he is "doubling down on medical marijuana;"

"I have met with hundreds of patients, dozens of scientists and the curious majority who simply want a deeper understanding of this ancient plant. I have sat in labs and personally analyzed the molecules in marijuana that have such potential but are also a source of intense controversy. I have seen those molecules turned into medicine that has quelled epilepsy in a child and pain in a grown adult. I've seen it help a woman at the peak of her life to overcome the ravages of multiple sclerosis.

I am more convinced than ever that it is irresponsible to not provide the best care we can, care that often may involve marijuana.

I am not backing down on medical marijuana; I am doubling down." (link)

This will certainly be one of the more interesting employment law issues over the course of the next few years, particularly given the lack of movement with respect to the federal prohibition on the use of marijuana.