That's what the New Democrats want to find out — and they're asking both House Speaker Andrew Scheer and the Commons' board of internal economy to investigate.
In a four-page letter to Scheer released Thursday, Ontario NDP caucus chair Malcolm Allen says that for more than eight months, Brown "dedicated his time and energy" to the leadership race.
"He took part in debates, interviews, partisan events and fundraisers," Allen said.
"None of these activities have anything to do with his work as member for the riding of Barrie" — or even, Allen said, "as a member of the federal Conservative caucus."
In fact, Allen suggests Brown may have actually "neglected" his parliamentary duties, as he missed 70 per cent of Commons votes held over that time period.
Allen also alleges the now former MP, who waited until after he had secured the leadership to officially vacate his MP's seat, chose not to take a leave of absence, which meant he was "still receiving his salary, paid for by taxpayers across the county."
NDP denounces 'kangaroo court'
But Allen's letter — and particularly the reference to the all-party committee that oversees MP and caucus spending — likely has at least as much to do with the ongoing controversy over the now-closed NDP satellite offices in Quebec City and Montreal as it does the newly installed leader of the provincial Tories.
The committee, which is chaired by the Speaker, is made up of six members — three Conservatives, two New Democrats and one Liberal.
Earlier this year, it concluded that 60-odd New Democrat MPs should be required to pay back $2.7 million in funds used to foot the bill for the out-of-town outposts, which the committee found were involved in partisan activities.
In response, the New Democrats have repeatedly denounced the committee as a kangaroo court, and have filed suit in federal court in an effort to overturn the decision.
On Thursday, Conservative whip John Duncan, who sits on the committee, confirmed that, as of July 1, House administration would begin rejecting expense and per diem claims filed by New Democrat MPs on the list of those deemed to owe money.
Neither Scheer's office nor the Ontario PCs have responded to a request for comment.