The UK's largest media organisations launched an assault last week against a change to the Civil Procedure Rules (CPR), which they say is an "unnecessary and disproportionate interference with the right to freedom of expression".
Associated Newspapers, News International and Trinity Mirror have instructed Reynolds Porter Chamberlain (RPC) to challenge the change, which came into force on Saturday (1 October).
General counsel at The Times Alastair Brett said: "It does appear to be a substantive rule change, which flies in the face of justice."
The group says that the CPR committee should have consulted on the amended rule before it came into force, but instead the amendment was sneaked in with the 40th update to the CPR among many other changes.
The amendment to Rule 5.4 says that anyone who is not party to a case may get hold of a claim form but is not allowed particulars of the claim, documents attached to the claim form and some names and addresses of claimants and defendants.
In a letter to the committee, RPC partner Keith Mathieson said the change would "further restrict the availability to the public of court documents and information concerning court proceedings".
The Department for Constitutional Affairs said the amendment was a "clarification" of existing rules rather than a change.