But a bill to do that has only attracted seven cosponsors, none of whom are Republican. Last year, a Senate bill that would amend the CSA to allow states to legalize weed — but not actually remove cannabis from Schedule I — attracted a handful of Republican cosponsors, including Gardner, and Sens. Rand Paul of Kentucky, Lisa Murkowski and Dan Sullivan of Alaska. Gardner will face a Democratic opponent in 2020 in a state that legalized recreational marijuana in 2014 and has drifted leftward in the years since.

While some oppose the pot-banking bill simply because they oppose pot, others say the proposal isn’t fully baked yet, and would make an already complicated area of law that much more tangled. That includes Joseph Lynyak, an attorney at Dorsey & Whitney LLP who represents cannabis businesses in California. While Lynyak calls the bill “a good start,” he’s worried it contains loopholes and ambiguities that will ultimately keep most financial firms from working with cannabis companies.

According to Lynyak, the bill would still allow a zealous federal prosecutor to go after individual investors in a cannabis business for aiding and abetting the transfer of funds to promote a criminal activity. While the bill provides safe harbor for firms that take a state-licensed pot business’s deposits or facilitates transactions, it does not explicitly protect individuals or firms that might buy shares in a dispensary or issue loans to a grower.

In its current form, the bill wouldn’t address a risk that only affects conglomerates, says Lynyak. Because it relies on the Dodd-Frank law’s consumer-focused definition of “financial service” in creating its safe harbor, the bill could be read as excluding holding companies from the regulatory risk protections. A bank could take deposits or provide loans directly to a subsidiary firm directly engaged in selling or growing weed, but offering those services to a parent holding company might still lead to civil liabilities, Lynyak argues. That would potentially create the rare barrier to entry that benefits smaller firms over deep-pocketed corporate giants.

In response, Woodbury said the bill’s definition of a “cannabis-related legitimate business” was broad enough to include a parent company. “If not, that’s the kind of technical change that can be easily made on the way to the floor,” he said. “There’s certainly no intent to exclude these corporate structures.”