MPs have rallied round one of their number who said he was being "intimidated" and prevented from exercising his right to freedom of speech in the Commons by a firm of solicitors.
On 14 January 2010, they backed a request from Liberal Democrat John Hemming to refer the matter to Committee on Standards and Privileges, who will now investigate.
A motion debated by MPs "called attention" to Mr Hemming's complaint that Withers LLP had "committed a contempt of the House by seeking to intimidate a Member in his parliamentary conduct".
Mr Hemming referred to an e-mail sent to him by Withers threatening legal action against him over allegations he made about a building development in his constituency.
Withers say they have acted "entirely properly and professionally" and "strongly refute" their actions were "intimidatory in any way".
Yesterday, in a highly unusual move, Commons Speaker John Bercow ruled that a debate could take place after Mr Hemming's complaint about the e-mail.
He also ruled that Hansard, the official record of Parliament, publish the e-mail in full.
Mr Hemming's motion was backed by the government, as well as the Tory and Liberal Democrat front benches.
MPs then referred the complaint to the committee without a vote.