Backers of new laws that legalized marijuana in Washington and Colorado were cautiously optimistic after President Barack Obama said Uncle Sam wouldn’t pursue pot users in those states.

Following the November votes in Washington and Colorado the Justice Department reiterated that marijuana remains illegal under federal law, but had been vague about what its specific response would be.

In a Barbara Walters interview airing Friday on ABC, President Barack Obama said: “It does not make sense from a prioritization point of view” to focus on drug use in states where it is now legal.

Marijuana activists were relieved at Obama’s comments, but had questions about how regulation will work. They said even if individual users aren’t charged with crimes, marijuana producers and sellers could be subject to prosecution, civil forfeiture and other legal roadblocks.