CNN, Politico and MS NOW are set to challenge the Trump administration in court after their journalists were shut out of the White House.
The three media organisations announced their plan on Monday, days after President Donald Trump ordered that they be barred from the White House.
The outlets said their reporters were stopped from entering the building on Saturday, with their press credentials also taken away.
Trump had announced the restriction on Friday, accusing the organisations of publishing “fiction or lies” about his administration. However, he did not point to any specific reports as the reason for the decision.
In a joint statement, the three outlets said their legal action would “protect our First Amendment rights and defend the principle that the government does not decide what the press reports or publishes”.
“Without notice or process, the White House revoked our journalists’ credentials because it objected to our reporting,” they said.
They further warned that “Left unchallenged, this threatens press freedom and the public’s right to independent journalism free from government interference.”
The First Amendment of the US Constitution protects freedom of the press, while US courts have historically considered government discrimination against media organisations based on their coverage to be constitutionally problematic.
Trump later defended the ban, saying “it’s really just cumulative stories over the last few years”. He also suggested that more media organisations could be affected.
Asked to clarify, Trump said: “Others to come in terms of fake news? Well, you know, the New York Times is fake news, the Washington Post is fake news.”
The dispute has also affected CNN’s role in covering Trump’s trip to the United Nations General Assembly in New York. The network had been scheduled to participate in the television press pool but its slot was left vacant, with Real America’s Voice listed as secondary crew.
The White House press pool provides coverage of presidential events and distributes material to other news organisations.
The administration assumed control of the press pool earlier this year, replacing the White House Correspondents’ Association, which had managed it for more than 100 years.
The latest dispute follows another confrontation between the administration and the Associated Press. AP journalists were restricted from certain White House locations after the administration objected to the outlet’s use of “Gulf of Mexico” instead of “Gulf of America”. The news agency subsequently filed a lawsuit.
Trump has also been involved in legal disputes with several other media organisations, including The New York Times, The Wall Street Journal and the BBC.