Green Party Co-Leader Elizabeth May says former Speaker Anthony Rota broke his own rules when he recognized in the House of Commons a Ukrainian Second World War veteran who fought for Nazi Germany.

According to House rules, the Speaker is the only member of the Commons who can call attention to a guest sitting in the gallery.

Although there are no concrete rules on who the Speaker can recognize, Chapter 7 of the House of Commons Procedure and Practice says the honour should be reserved for foreign dignitaries, members of provincial and territorial governments and "Canadians who have distinguished themselves in any field of endeavour by their achievements, deeds or success of national or international scope."

It's that last category that has May taking issue with Rota's decision to recognize Yaroslav Hunka during Ukrainian President Volodymyr Zelenskyy recent visit to the House of Commons.

May said that on a number of occasions during the House's spring sitting, she asked Rota if he would recognize people she thought would fit the category of "distinguished" Canadians — including noted environmentalist David Suzuki — but was rebuffed.

In April, Rota sent an email to MPs reminding them of the guidelines on who can be recognized by the Speaker. The email seemed to set a high bar for "distinguished" Canadians, listing Nobel prize winners as the only example.

May said Rota didn't apply that level of scrutiny when he recognized Hunka.

"He broke his own rules. This should have never happened," May told CBC News.

Rota has said he was unaware of Hunka's past when he invited and recognized him in the House. The former Speaker has been criticized for not fully vetting his guest.

But May said more vetting wouldn't have been necessary had Rota applied the rules fairly.

"I don't think we needed vetting. We just needed thinking," she said. "We just needed to think it through."

CBC News has reached out to Rota for comment.

A spokesperson for the Speaker's office said that when a distinguished guest like Zelenskyy gives a joint address to Parliament — which includes both MPs and senators — the House isn't technically sitting and typical practice doesn't apply.

A similar situation unfolded when U.S. President Joe Biden addressed Parliament in March. Prime Minister Justin Trudeau acknowledged the presence of Michael Kovrig and Michael Spavor, even though the rules state that only the Speaker can do so when the House is in session.

May said she was "shocked" by the response from the Speaker's office.

"The rules should have had even more application in a setting as sensitive as the sitting for a foreign leader's speech," she wrote in an email to CBC News.

Former Speaker Geoff Regan told CBC News that "distinguished Canadians" generally means winners of major awards, such as the Governor General awards, or Olympic champions. He added the Speaker has some leeway over who is recognized.

"You have fairly broad discretion, but whenever you have discretion you want to exercise it with good judgment and with care," Regan said.

There have been instances in the past of guests being recognized by the Speaker who may not have met the high bar Rota cited in his April email to MPs.

In 2006, hockey commentator Don Cherry was recognized by Speaker Peter Milliken — that gesture met with a mixed reaction from MPs. In 2003, Milliken also recognized Ryan Malcolm after the singer triumphed on the reality TV show Canadian Idol.

The late Eugene Melnyk, former owner of the Ottawa Senators, was also acknowledged by Speaker Andrew Scheer in 2014.