Arizona Gov. Jan Brewer has signed a bill that would allow public colleges and universities to conduct medical marijuana research.
Brewer's action Tuesday comes roughly a year after she signed a bill banning medical marijuana on higher education campuses.
Critics say last year's law was too strict.
The new law would benefit a University of Arizona researcher studying whether medical marijuana helps veterans with post-traumatic stress disorder.
Senate Bill 1443 passed with near unanimous support from the GOP-led Legislature.
Arizona voters legalized medical marijuana in 2010, but state officials fought implementation at length. Several clinics have opened around the state in the last few months.