Earl Turcotte, who quit the federal public service in protest over the issue, levels the allegation in a written submission to the House of Commons foreign affairs committee, which is holding hearings on the bill.
Bill C-6 faces widespread international condemnation, including from the normally neutral International Committee of the Red Cross, because of a clause that would allow the Canadian Forces to be involved in the use of cluster bombs in joint operations with non-treaty signatories such as the United States.
Critics say that would undermine the intent of the treaty — banning the use of an imprecise weapon that has proven particularly harmful to civilians.
Turcotte says he gave assurances to Canada's international partners during the negotiations that it would not use a section of the treaty that allows interoperability with non-party states as a "loophole" to use cluster bombs.
"As Head of Delegation, I made all statements for the Canada during plenary negotiations. I know what I said on behalf of our country, with political and official-level support at that time. I also know how it was understood and ultimately agreed by all 108 negotiating states," Turcotte states.
"Bill C-6 constitutes a reversal of many of the key commitments Canada made during negotiations and by signing the convention in 2008 and is an affront to other states that negotiated in good faith."
Turcotte says the government is misinterpreting a key clause in the convention he helped write and negotiate, known as Article 21, that allows for military co-operation between signatories and non-party states.
Turcotte says the article was designed to allow Canadian troops to participate in a joint operation with the U.S. but not to "aid or abet" the use of cluster bombs.
Foreign Affairs Minister John Baird told the committee last week that the clause is necessary to preserve Canada's unique military relationship with the U.S., which includes giving senior Canadian officers access to high-level exchange programs.
One of the Canada's former top soldiers, retired general Walt Natynczyk, also backed the clause in testimony last week. Natynczyk served as a deputy commander of U.S. forces in Iraq in 2004, even though the Canadian government opted out of the war, because he was part of a high-level secondment.
"The convention itself, specifically section 21, contemplated this," Baird said in an interview. "We have probably the most integrated defence and security relationship of any two countries in the world."
During a news conference on Sunday, Baird told reporters that, "There'll be no member of the Canadian Armed Forces dropping clusters bombs on anyone, ever."
In his submission, Turcotte rejects Baird's general argument about preserving the military relationship with the United States as "utter and complete nonsense."
"If there was any suggestion during negotiations of the CCM that such activities could be allowed by Article 21, it would never have been accepted by other negotiating states, and I would never have put it forward," he writes.
Turcotte says Article 21 is "largely based" on wording that he personally drafted.
"As one of its authors and one of those who fought hardest for its inclusion in the final text, I think I understand its provisions and restrictions as well as anyone in the international community."
Turcotte says there was "intense debate" between the Foreign Affairs department, where he used to work, and National Defence about how to interpret Article 21 — an argument that he and his department eventually lost.
As a result, Turcotte issued a "conscientious objection" and resigned after nearly three decades in the federal public service.
Turcotte now works for the United Nations Development Program in Laos, as the agency's chief technical adviser in the unexploded ordnance sector. Laos is the country most heavily contaminated by cluster bombs, per capita, a legacy of the nine years of American carpet bombing during the Vietnam War.
The committee hearings resume Tuesday.