Adam Carroll had been expected to testify before the ethics committee Thursday about his role in the Twitter account Vikileaks.
He was supposed to appear earlier this week but was ill and the committee decided they'd issue a summons for his return.
But in a letter to committee members, his lawyer says Carroll is still too sick to attend.
The letter says Carroll isn't refusing an invitation to appear before MPs and will eventually testify, as he wants to bring the issue to a close.
"However, this appearance will be by invitation, not compulsion," said the letter from lawyer Paul Champ.
In the letter, Champ contends the committee had no jurisdiction to formally summon Carroll after he failed to appear earlier this week.
The Tory-dominated committee had called Carroll to testify after an investigation by the House of Commons suggested he was using parliamentary resources to post Public Safety Minister Vic Toews' divorce details via Twitter.
The account was set up in the wake of the introduction of an online surveillance bill that would give authorities expanded powers to gain people's Internet information — drawing the ire of critics who said it was too intrusive.
While the divorce records were already in the public domain, using the Commons computer to distribute them may have violated acceptable-use policies.
Carroll had quit his job once he was identified as the source of the account and Liberal Leader Bob Rae apologized to Toews in the Commons.
As a result, the Speaker of the House of Commons declared the matter closed.
For that reason, the committee has no real authority to be studying the issue, Champ wrote.
"As a consequence of Mr. Rae’s apology and the Speaker’s ruling, the matter of the Vikileaks30 account was found not to be a prima facie violation of privilege and was not referred to the Standing Committee on Procedure and House Affairs for inquiry," the letter says.
"The Access to Information, Privacy and Ethics Committee is clearly attempting to sneak in through the back door an inquiry into Vikileaks30 contrary to the Speaker's ruling on this matter."
Tory MP Dean Del Mastro, who led the charge to have Carroll appear at committee was unavailable to comment.
On Tuesday, Del Mastro had said a doctor's note was required to give Carroll permission not to appear.
The committee's next steps on the matter are unclear. The meeting scheduled for Thursday has now been moved entirely in camera, meaning any discussion of the issue won't be public.
Members could ask the Speaker to issue a warrant to compel Carroll's testimony, if they don't accept the doctor's letter that Champ said he is working to obtain.
But, Champ stressed, Carroll does intend to appear at some point.
"As previously indicated, (Carroll) remains willing to voluntarily appear and respect the invitation that was originally extended to him on March 8, 2012," the letter said.
"Ultimatums and threats without legal foundation are unnecessary, undignified and abusive."
While the Speaker had ruled the Vikileaks account wasn't a breach of privilege, he had declared that a series of videos targeting Toews and posted by activist group Anonymous did constitute a breach.
The videos were part of what Toews had said were a broader campaign of threats against him following the introduction of the Internet surveillance bill.
A different committee in the Commons will begin a discussion of that issue Thursday.
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