Pennsylvania's recently launched medical marijuana program may have unintentionally created a minefield that employers and patients across the state have only begun to navigate:

Patients who use marijuana could end up losing their jobs as a result.

At a fact-finding hearing in Philadelphia City Council on Wednesday, a panel of lawyers, business interests, and medical professionals hashed over the murkier employment issues stirred up by the law.

The upshot: Patients currently have few — if any — workplace protections. And until a lawsuit is filed, it's unlikely that patients will know how strong those protections might be.

The murkiness results from the difference between state and federal law. Pennsylvania legalized medical marijuana in 2016, and last month commercial dispensaries in the state began distributing the medicine. However, under federal law, all forms of marijuana are considered illegal Schedule 1 substances with a high potential for abuse and no medical applications.

Pennsylvania law contains a provision that explicitly bars employers from firing or otherwise discriminating against patients solely because they're participating in the program. That provision is untested. There are no court decisions in Pennsylvania that have interpreted it.

Complicating matters, the City of Philadelphia — and many private businesses — must comply with the federal Drug Free Workplace Act.

"And under the law you can fire [someone] if they fail a drug test," said Josh Horn, the co-chair of Fox Rothschild's Cannabis Law practice, who testified at the hearing. "An employer has no obligation to accommodate someone if they use cannabis during work hours."

But there's a sizable loophole, noted Pedro A. Rodriguez, director of the city's Office of Human Resources.

"The [state law] does not require that employers conduct mandatory drug tests," Rodriguez said.

Employers can institute zero-tolerance policies for workers in "safety sensitive" positions. Those jobs would include any that require driving, the use of machinery, or public safety, he said.

State law prohibits medical marijuana patients only from handling certain chemicals, operating high-voltage electricity, and performing duties at heights or in confined spaces, said Horn.

"A patient can't perform work that could be life-threatening," Horn said in an interview.

The city's drug and alcohol policy prohibits all city employees from possessing or using drugs or alcohol while on city property, Rodriguez said. And official policy negotiated with three of the city's unions — AFSCME, District Council 33, and District Council 47 — requires employees to disclose to the city if they are on any medication that may alter their ability to operate machinery or motor vehicles.

"As you can see, balancing federal and state law with the medical needs of our employees is not easy, but we welcome the opportunity to be a part of this important conversation," Rodriguez said.

Traces of marijuana may remain in a patient's system for up to 30 days and drug tests can't distinguish whether it was consumed during work hours, said Samira Harris, a nurse at Albert Einstein Medical Center and a member of the board of the Pennsylvania Association for Staff Nurses and Allied Professionals.

"Medical professionals should never be at work while under the influence of any prohibited substance," Harris said. "But what about a medical professional who is also a patient, who only uses medical marijuana during their off hours?"

Councilwoman Cherelle Parker, who said she backed the state's medical marijuana program,  said she had called the hearing as a way of providing guidance to the city and business "because the law is vague."

"There are potential unintended consequences that the legislation could have on employers and employees," Parker said. "It's important that the private sector drive this. Now the work really begins."