Twitter just started censoring searches for "marijuana," "cannabis" and other drug-related terms. Yet searches for tweets on "opioids" show up just fine.

Twitter is a platform that many activists use to spread information about important policy issues like marijuana legalization and medical cannabis. Journalists use Twitter to research stories and stay up to date on developments. And elected officials use Twitter to keep their finger on the pulse of what their constituents care about.

More than half the states in the U.S. now allow medical cannabis, and a growing number of states are adopting full legalization. There is even now a federal law on the books protecting states with medical marijuana laws.

Censoring marijuana-related searches prevents serious people from communicating about one of the most prominent policy issues of our time.

BACKGROUND: Without warning, Twitter recently instituted a "sensitive content" filter that is automatically turned on for many users, and the settings to disable it are hidden. As a result, queries for topics that Twitter has designated "sensitive" yield zero results on the search tab for latest tweets.