John Ross has written a very thorough Reason article documenting all of the measures for liberalizing marijuana laws likely to be considered at the state level in 2014. He counts 13 states that are considering following Colorado and Washington’s lead in legalizing marijuana possession for recreational use, and 16 that may join the 20 states that currently permit medical marijuana.

Not all of these laws are likely to pass. But if a large number do, it could greatly accelerate the trend towards marijuana legalization. This is especially true if legalization hits large states such as California, where a legalization ballot initiative narrowly failed in 2010; public opinion in both California and the nation as a whole has become more favorable to legalization since then. Even many conservatives have begun to rethink the War on Drugs.

Even if numerous states legalize marijuana, the drug will still be illegal under federal law. In its badly misguided decision in Gonzales v. Raich (2005), the Supreme Court ruled that Congress’ power to regulate interstate commerce allows it to ban the possession of marijuana even in cases where the marijuana in question has never crossed state lines or been sold in an market anywhere. The Obama administration has taken a very equivocal position on the question of whether federal prosecutions for marijuana distributors will continue in states that legalize marijuana under their own laws. However, widespread legalization at the state level will put pressure on the federal government to repeal the federal ban. Even if it does not, federal law enforcement resources are extremely limited, and it will be difficult or impossible for the feds to enforce a marijuana ban without state cooperation. If marijuana legalization does sweep the nation over the next few years, perhaps it will also lead more people to reconsider the War on Drugs as a whole.