How stringently are the marijuana laws prosecuted in Austin, Texas?

I am the caregiver and roommate for a friend with mental illness. I don't personally use it, but my friend smokes about 1 ounce every two weeks to stabilize his mood, and it seems to be helping him more than the psych meds. We once lived in CA where he was eligible for medical marijuana for his condition. Austin seems like it would be a much more tranquil, progressive place for us to live than our current home in Miami Beach. However, I've read that in Texas, people are routinely jailed for possession of even small amounts of marijuana. I know Travis County is more liberal than the other areas of Texas, but can someone tell me what types of penalties and fines are generally essed in that area for possession of less than one ounce? My friend has prior convictions for possession in PA, FL, LA and VA, if that's a consideration. Thanks for your feedback!