Facebook is relying on both local organizations (such as political parties, groups on either side and the Transparent Referendum Initiative) and integrity-focused machine learning to police ads. The company has promised eventual anti-interference tools that include a "verification process," but those aren't completely ready. The moratorium on foreign ads will act as if those tools are in place today, Facebook said.

The Irish referendum could be a litmus test for Facebook's ability to curb electoral interference going forward, especially in the American mid-term elections this November. The tech giant wants to show that the dark days of Russian meddling are over, both to protect its reputation and to head off regulations that might dictate more of the content it allows. If it works, Facebook might gain (or regain) the trust of those convinced it's being used as a political pawn.