The data leak is just the most recent example of abuse on the site, following reports of Russian meddling during the 2016 U.S. presidential election and controversial Brexit vote in the UK.

Facebook in recent months has sent representatives to Washington to address issues of foreign interference on Facebook, but this week’s hearings will be the company’s first opportunity to address privacy policies before lawmakers and Zuckerberg’s first appearance before Congress.

It’s one of two Capitol Hill appearances for the Facebook founder and CEO this week. Zuckerberg is also scheduled to appear before a joint hearing of the Senate Judiciary and Commerce committees Tuesday.

Facebook is facing questions following reports that research firm Cambridge Analytica improperly gained access to the personal information of as many as 87 million Facebook users.

Facebook is facing questions following reports that research firm Cambridge Analytica improperly gained access to the personal information of as many as 87 million Facebook users.