CNN, Politico and MS NOW have said they will sue the Trump administration after the three US media outlets were barred from the White House.
President Donald Trump announced the ban on Friday, accusing the three organisations of writing "fiction or lies" about his government.
The companies said their reporters were denied access and had their badges seized when attempting to access the building on Saturday.
In a joint statement on Monday, they said they were pursuing legal action to "protect our First Amendment rights and defend the principle that the government does not decide what the press reports or publishes".
The First Amendment forbids the government from "abridging" the freedom of the press - language that courts have traditionally interpreted as preventing the government from discriminating against the media based on the content of their coverage.
"Without notice or process, the White House revoked our journalists' credentials because it objected to our reporting," the CNN, Politico and MS NOW statement continued.
"Left unchallenged, this threatens press freedom and the public's right to independent journalism free from government interference."
