Are you really asking, or are you spinning wheels?
Practically speaking, with financial support, he could have likely had a better defense, with better extrinsic force brought to bear.
And more broadly, well funded popular campaigns to remove the officials who executed these legal actions. I don't know if it happened in his case, but usually some local officials reache out to the feds to help them contravene California law. If those officials knew that they would be losing their positions of authority if they initiated federal prosecution, I doubt they'd be so eager.
And more proactively, sheriffs can be installed via well funded and executed campaigns, who carry out California law and protect growers and end user providers from federal involvement in California's affairs.
And way more proactively, popular campaigns advocating the removal of the federal prosecutors in California who are violating California law.
And way way way more proactively making this a campaign issue for Obama. It is clear some kind of deal was reached for funding, but if Barry O stood an actual chance of not carrying California... the fed attack dogs would be gone and federally subsidized joint rollers would be all over the state.
Just a few potential avenues off the top of my head.