'We could block a whole lot more investments than we are and be still one of the most open regimes in the world," declared the nation's prime minister.
But foreign investments into this country are currently facing problems: vague, all-encompassing legislation; discretion to politicians to approve oil and gas deals as they see fit; the shadowy influence of domestic lobbies.
The Investment Canada Act, passed in 1985, gives the government the power to block foreign acquisitions of domestic companies unless they provide a "net benefit" to the nation. Not invoked until 2008, this provision has now been used three times in three years in major natural resources deals.
In 2010, BHP Billiton's US$39 billion (Dh143.25bn) bid for the world's biggest fertilizer firm, Potash, was rejected. Last month, Canada stopped the Malaysian national oil company Petronas from buying Progress Energy, a gas producer, for $5.2bn. Petronas has 30 days to revise its application.
And on Friday, a review of the $15bn takeover of the oil corporation Nexen by the state-owned China National Offshore Oil Corporation was extended until next month.
"The real issue is, are we going to get that reciprocal openness in other countries?" asked Stephen Harper, the prime minister, who wants to tie inbound foreign investment to the ability of Canadian firms to invest in other countries.
This might be an acceptable short-term tactic. But if adopted as a permanent principle, it promises a balkanised investment world, a patchwork of bilateral deals and compromises.
Canada clearly benefits from foreign investment, particularly in its resources sector. Its oil sands, one of the world's largest deposits, hold at least 169 billion recoverable barrels.
Canada may have an estimated 388 trillion cubic feet of shale gas, and Progress Energy, among others, is developing these resources in British Columbia for export to Asia.
As well as the $2.5bn premium Petronas is paying, the creation of thousands of jobs and billions of dollars of investment in gas production amount to benefits that should surely outweigh any concerns on the debit side.
Of course, all governments retain the right to block transactions on grounds of national security or monopoly. But "net benefit" requirements on acquirers, such as demands to retain local jobs or process minerals locally, reduce the value of Canadian companies, and hence impose a hidden "net loss" on investors.
Canadian natural resources companies trade at a discount, and the oil sands in particular are enormously hungry for capital, compared to the relatively small domestic economy.
Canada thus benefits from foreign investment whether reciprocal or not. If China persists in turning away highly capable and technologically advanced Canadian companies, that is its problem.
Beyond reciprocity, domestic political considerations may be important. Mr Harper may be worried about seeming too friendly to Chinese investment.
Blocking the Petronas deal gives cover for objecting to China National Offshore Oil's acquisition; Mr Harper can claim to be even-handed between the Chinese and others.
Or it may be intended to warn British Columbia's provincial government to stop raising difficulties over pipelines crossing its territory to the Pacific.
But these kind of murky undercurrents are exactly what western investors have long objected to Algiers, Baghdad, Caracas or Delhi.
As Peter Julian, the natural resources spokesman of the opposition New Democrats, said: "There will be serious implications if they keep making things up on the back of a napkin.
"Investors will lose confidence … This no way to run a large economy."
Capital-short western countries should be taking the lead in encouraging an open global market.
Mr Harper has promised clarification of the foreign investment rules. Ottawa needs to ensure that, unlike in many other countries, they are not simply cover for short-sighted protectionism.
Robin Mills is the head of consulting at Manaar Energy and the author of The Myth of the Oil Crisis and Capturing Carbon