Oklahoma City — Oklahomans responded with an outcry when the state Department of Health proposed limiting THC in medical marijuana, but there's little clear evidence on whether a cap would hurt or help patients.

State Question 788, which passed in late June, legalized the sale and possession of marijuana plants and products without a limit on tetrahydrocannabinol, the chemical that produces euphoria in marijuana users. Regulations passed by the state Board of Health on July 10 created a cap at 12 percent THC in finished products and 20 percent in mature plants.

The board may have to change that regulation, however, after a letter from Attorney General Mike Hunter on Wednesday suggested board members may have overstepped their authority to regulate medical marijuana.

More than 500 of the 1,034 public comments the Health Department released on the proposed rules earlier this month objected to the THC limits. Some commenters said it would be impossible to control the level of THC in plants. Others, like Noel Treadwell, said that doing so would make medical marijuana largely worthless.