One year ago, she used her first question in the House of Commons to ask the government if it was going to be hiding any major new laws in its upcoming budget implementation bill for that year.
Before being elected her party's first MP, she'd watched from afar as the Conservatives used omnibus bills to get through contentious pieces of legislation and she was concerned about the trend.
Finance Minister Jim Flaherty told her the 2011 bill would be strictly budget-related and he kept his word.
It was a tidy four dozen pages of non-controversial measures like taking the HST off poppy sales.
May even voted for it.
At the time, she said, she thought that perhaps the Conservatives were no longer going to use omnibus bills, given they had a majority government.
"They could get anything passed they want without using this kind of stealth mechanism of throwing them in a budget implementation bill," she said.
"So, I really was not prepared for this year's budget."
At over 400 pages, the budget amends some 70 pieces of legislation on everything from environmental assessment to the regulation of charities.
As the lone Green party MP in the Commons, there are few avenues available to May to make changes to proposed laws.
So she's throwing everything she has at this one.
In addition to asking the Speaker to rule the entire bill out of order, she and her staff burned the candle at both ends for weeks to put together 330 amendments to the bill.
Her suggestions join over 1,000 others being made by the New Democrats and the Liberals.
But they are a bit different.
The amendments going before the Commons this week proposed by the New Democrats and Liberals seek to delete elements of the contentious legislation.
They can't suggest actual changes at this point due to a rule that requires those suggestions to be dealt with at parliamentary committee.
They were put forward at committee and were rejected by the Conservatives.
But because her party doesn't have official standing in the Commons, May doesn't have an active seat at the committee table so she can't suggest changes to bills there.
Her de facto independent MP status also means she has fewer opportunities to quiz the government during Question Period and sometimes requires permission of the rest of the Commons to get up and speak.
Earlier this year, she was denied the opportunity to speak during a tribute to the late Czech president Vaclav Havel and on Remembrance Day.
But that hasn't stopped her from trying to find a voice.
May now deploys a team to keep on top of issues at committee so she's ready to use what legislative arrows exist in her small parliamentary quiver.
Last year, she held up efforts of the Tories, Liberals and NDP to fast-track a mega-trials bill when she denied to join in the requirement that it have unanimous consent.
The introduction of substantive amendments to a bill when it comes back to the Commons after committee hearings is another tactic and the one she's using on the budget bill.
May said she's drafted her amendments to the budget bill with a eye towards the Conservatives' intention with the bill.
"I've tried very hard to be respectful. They do have a majority in the house," she said.
"What I don't respect is that it's illegitimate to put all these changes in a budget bill."
For example, May said she understands that with changes to the environmental assessment process, the Conservatives want to speed up hearings and not duplicate efforts at the federal and provincial levels.
"I've respected those two elements that they say they want but what they did in C-38 is just massive vandalism to environmental laws with what they claim is their purpose," she said.
The Conservatives have accused their critics of playing political tricks at the expense of the Canadian economy by introducing so many amendments, but May says they are missing the point.
"We have an obligation to review legislation and to do our very best to prevent bad legislation from passing and to improve it through the process," she said.
"That's our right. It's not some kind of game."
The Speaker is to decide Monday how those amendments will be handled in the House.
Andrew Scheer could do everything from throwing them all out of the window to bundling them together to keep down the number of votes required.
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