SAN FRANCISCO — These are heady times for advocates of legalized marijuana in California — and only in small part because of the newly relaxed approach of the federal government toward medical marijuana. State lawmakers are holding a hearing on Wednesday on the effects of a bill that would legalize, tax and regulate the drug — in what would be the first such law in the United States. Tax officials estimate the legislation could bring the struggling state about $1.4 billion a year, and though the bill’s fate in the Legislature is uncertain, Gov. Arnold Schwarzenegger, a Republican, has indicated...