Representatives from Facebook and Google are on Capitol Hill Tuesday morning, appearing alongside civil rights activists and a prominent right-wing activist for a hearing about how social media platforms are used by white supremacists as lawmakers explore possible legislative options on the issue.

The hearing, which is being held by the House Judiciary Committee, comes just a few weeks after a terror attack in New Zealand that was streamed live on Facebook. Fifty people at two mosques were killed in the attack.

The representatives from the tech companies’ policy teams are part of an eight person panel, which also includes representatives from civil rights groups such as the Anti-Defamation League and Candace Owens of the conservative group Turning Point USA.

Social media networks have been criticized for the role their platforms can play in spreading extremist ideologies and radicalizing people, and for the lack of action they’ve taken on the problem of white supremacists and nationalists on their sites. Among those under fire are Facebook and Google, which owns the video sharing site YouTube, which has been criticized for hosting such content and for algorithms that can create a “rabbit hole” that takes users into more extreme videos.

Two weeks after the New Zealand massacre, Facebook announced that it would ban all “praise, support and representation of white nationalism and separatism” on Facebook and Instagram. Previously, the company had banned white supremacy, but had viewed white nationalism differently. The company said it had decided to ban white nationalism after months of consultation with civil rights groups.

Neither Google-owned YouTube nor Twitter have enacted similar blanket bans of white nationalism but both companies say they have policies to fight hate and the incitement of violence on their platforms.

A livestream of the hearing on YouTube included user comments, and before the hearing even started a number of racist and anti-Semitic comments had been added.