Twitter is being sued by the widow of an American killed in Jordan, accusing the social media giant of giving a voice to Islamic State (ISIS).
Tamara Fields, a Florida woman whose husband, Lloyd, died in the November 9 attack on the police training centre in Amman, said Twitter knowingly let the militant Islamist group use its network to spread propaganda, raise money, and attract recruits.
She said the San Francisco-based company had until recently given ISIS an "unfettered" ability to maintain official Twitter accounts.
"Without Twitter, the explosive growth of ISIS over the last few years into the most-feared terrorist group in the world would not have been possible," the complaint, filed on Wednesday in the federal court in Oakland, California, said.
Fields accused Twitter of violating the US Anti-Terrorism Act, which allows triple damages for providing material support to terrorists.
Her lawyer said he believes it's the first case in which a social media company has been accused of violating that federal law.
The lawsuit may add to the pressure that social media companies face to take down posts associated with terrorist groups.
"While we believe the lawsuit is without merit, we are deeply saddened to hear of this family's terrible loss," Twitter said in a statement about the civil lawsuit. "Violent threats and the promotion of terrorism deserve no place on Twitter and, like other social networks, our rules make that clear."
Fields may face an uphill battle to prove that Twitter knew or should have known its technology was helping terrorists.
"We certainly know social media plays an important role in allowing ISIS to recruit foreign fighters," said Jimmy Gurule, a University of Notre Dame law professor and former US Treasury Department official specialising in terrorist financing.
"But at the end of the day, is there a sufficient nexus between ISIS' use of Twitter and acts of terror? I'm not saying you can't show it, but it's a real challenge."
In November, ISIS sympathisers launched an attack against the FBI and CIA, and hijacked over 54,000 Twitter accounts in retaliation for a drone strike that killed a British ISIS extremist.
In Twitter's most recent biannual transparency report, released almost a year ago, it was revealed that the Australian government made only 10 requests for user account information during the second half of 2014, and zero account removal requests for the entire year.
Governments worldwide made a total of 2,871 account information requests, with the majority originating from the US, Turkey, and Japan.
The Office of the Children's eSafety Commissioner was launched last year by the Australian government to appropriately deal with content that has been posted on social media sites in the country.
The department, headed by eSafety Commissioner Alastair MacGibbon, has the power to force large social media companies, such as Twitter, to remove content deemed to be of a bullying, offensive, or illegal nature. Those that do not comply face fines of AU$17,000 per day.
The federal government has previously committed a total of AU$2.4 million over four years to create and run the eSafety commissioner's office, which falls under the jurisdiction of the Australian Communications and Media Authority (ACMA).
The idea was first floated in November 2012, when former Parliamentary Secretary for the Minister for Communications Paul Fletcher released a discussion paper outlining proposals for a way to tackle online safety for children. Since then, the government has introduced the Enhancing Online Safety for Children Bill 2014.
A spokesperson for Fletcher told ZDNet last year that Twitter's latest report on how many removal requests the government has made is not indicative of how many online bullying cases the commissioner would potentially deal with.
"Twitter notes in its transparency report that 'Governments generally make removal requests for content that may be illegal in their respective jurisdictions', such as 'defamatory statements', or 'prohibited content', as distinct from cyberbullying content," he said.
"The powers that will be granted to the children's eSafety commissioner relate only to cyberbullying material targeted at an Australian child. This is a quite different matter to existing legal grounds for content to be removed (such as the grounds Twitter has referred to). Therefore, existing removal requests give no indication of the extent of cyberbullying cases."
In October, the eSafety office released statistics on its first three months of operation, which saw the office complete 2,057 investigations into illegal online material, most of it child abuse material, with content removed from the internet within one to three working days through the INHOPE network.
More than 600 children were referred to Kids Helpline, and 40 cases of serious cyberbullying were handled through the office's complaints process. More than 5,200 students participated in the office's virtual classrooms program.
MacGibbon's office also announced partnerships with Facebook, Instagram, YouTube, Google+, Twitter, Yahoo Groups, Yahoo Answers, and Ask.fm, all of which are cooperating to take down seriously harmful material in less than 12 hours.
"The level of cooperation is remarkable," MacGibbon said at the time.