HARRISBURG -- Proponents of allowing medical marijuana use in Pennsylvania filled a Senate hearing room Tuesday, describing their hopes that components of the plant could help children with seizures and veterans with post-traumatic stress disorder.

Senators on the Law & Justice Committee heard from mothers who said their children have suffered not just from severe seizures but also from the medications prescribed as treatment. One mother urged legislators to put aside "preconceived notions" of cannabis.

Joe Mirt, a Pennsylvania Army National Guard combat veteran who lives in Carrick, described his attempts to cope with what he suspects to be PTSD through alcohol and then through medications that were accompanied by serious side effects.

"I never thought about killing myself more than when I was on those pills that they were giving me to help what I was going through," he said.

Eventually, after a diagnosis of multiple sclerosis, he tried finding relief through marijuana, which he said relieved his headaches, cleared his vision and allowed him to get out of bed for the first time in days.

Twenty states and the District of Columbia have permitted medical marijuana, while Colorado and Washington recently approved recreational use.

Committee chairman Chuck McIlhinney, R-Bucks, said the hearing was intended to gather information as the committee considers legislation that would allow cannabis use for certain serious medical conditions. He said he has no immediate plans to call a vote.

The legislation faces serious obstacles. Gov. Tom Corbett has said he would veto such a bill because marijuana remains illegal under federal law.

The Pennsylvania Medical Society opposes recreational marijuana use but believes further research is needed on medical marijuana, said Michael Fraser, executive vice president and CEO, while the Pennsylvania State Nurses Association supports the bill.

The testimony had an effect on at least one member, Sen. Anthony Williams, D-Philadelphia, who said he had entered as a skeptic but had decided to co-sponsor the legislation. Members of the audience greeted his words with applause.