A bill that would allow cannabis oil to be used in the treatment of intractable seizures as part of a clinical study passed in the Senate Wednesday by a 23-4 vote.

The bill stipulates that the oil, containing less than nine-tenths of a percent of tetrahydrocannabinol, the main psychoactive ingredient in marijuana, could only be produced and dispensed to hospitals by Tennessee Technological University, and that the law would expire in June of 2018.

Those provisions were included to address skepticism from lawmakers about the effectiveness of medical marijuana, which has hampered legislation like this year’s Koozer-Kuhn Medical Cannabis Act.

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