Facebook and Google are appearing on Capitol Hill more often these days.

Over the past few years, services run by Facebook, Google and other tech giants have become home to increasingly more vocal and violent extremists. And now Congress wants to understand what they're doing about it.

On Tuesday, Facebook and Google will send representatives to Capitol Hill to discuss this issue before the House Judiciary Committee. The hearing will be attended by Neil Potts, who oversees Facebook's content policy team, and Alexandria Walden, a counsel for free expression and human rights at Google.

The hearing was prompted by last month's massacre in Christchurch, New Zealand, in which a terrorist attacked two mosques, killing 50 people and injuring 50 more. What made the attack more shocking was that the shooter livestreamed the killings on Facebook, prompting people to download copies and spread them across the internet. The video's spread -- and Facebook's, Google's and Twitter's seeming inability to stop it -- raised questions about what these companies are doing to prepare and prevent these types of incidents from spreading on their services.

For its part, Facebook said in late March that it's banning white nationalist and white separatist content from its service after consulting civil rights groups. Both Facebook and Google say they've hired thousands of people to respond to bad behavior on their services. The companies also say they've developed artificial intelligence tools to more easily identify these types of posts before they spread.

When it comes to tech and politics, the conversation is much broader than privacy and the spread of extremism. President Donald Trump and prominent conservatives are also concerned about what they believe is systematic censorship happening on social media.

"There are a great many Americans who I think are deeply concerned that Facebook and other tech companies are engaged in a pervasive pattern of bias and political censorship," Sen. Ted Cruz of Texas said last year during a hearing with Facebook CEO Mark Zuckerberg. "To a great many Americans that appears to be a pervasive pattern of political bias."

On Wednesday, the day after the House hearing, the Senate will meet to discuss "Stifling Free Speech: Technological Censorship and the Public Discourse." Representatives from Facebook, Google and Twitter are expected to attend.

Here are the details for the House hearing:

Tuesday, April 9 at 7 a.m. PT/10 a.m. ET. 

It will be livestreamed on the committee's YouTube page here. We'll have the video playing on this page when it begins as well.

The hearing itself will take place in room 2141 in the Rayburn House Office Building in Washington, DC.

Facebook and Google have stepped up their public discussion of white nationalism on their services and will likely offer data similar to what they've made public before. 

Facebook in particular has also begun publicly advocating more regulation of the tech industry, following an opinion piece Mark Zuckerberg wrote for The Washington Post last month.

Originally published April 8, 5 a.m. PT.Update, 1:29 p.m. PT: Adds details about Senate hearing next day; Update, April 9 at 6 a.m.: Adds more information about Christchurch attack.

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