As Tennessee lawmakers debate a bill that would legalize some forms of medical marijuana, public perception of the drug is growing more positive.

"Support for the legalization of marijuana, fully, medical and beyond, has actually been on the rise for some time," said Dr. Tricia Bruce, an associate professor of sociology at Maryville College. "Some 6 in 10 Americans support legalizing marijuana fully, and the numbers are even higher for medical marijuana."

HB 1749 advanced in a House subcommittee Tuesday. It would allow cannabis oil be used for medical purposes.

Tennessee Bureau of Investigation agents testified against it.

"The factors affecting drug use are very plain. price, availability, perception of risk and public attitude," said Tommy Farmer with the TBI Drug Investigation Division. "And this is one of the reasons we do not support this one."

The bill currently has four sponsors in the House. That includes Speaker of the House Beth Harwell and Bob Ramsey from Maryville.

Like the same-sex marriage debate, experts say public opinion on marijuana is shifting.

"You had a really rapid upward trend in support for same sex marriage and then the legalization of same sex marriage at the federal level. So we're seeing marijuana follow that same trend line," Bruce said. "Younger Americans are more likely to support the legalization of marijuana that older Americans."