The exposure of secret, big-ticket fundraisers held by governing parties in Ontario and B.C. has shed light on the patchwork quality of party finance laws across the country, leading some to call for greater uniformity in the way political donations are regulated.

The degree of stringency in regulations for political contributions in Canada covers a broad range.

While disagreement remains about how best to crack down, critics say the integrity of the political process is at stake.

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Democracy Watch, an advocacy group, is urging provinces to adopt Quebec's model: Individuals can donate only $100 a year to political parties, plus another $100 during elections, and union and corporate donations are banned.

"Quebec has it right," said Duff Conacher, the organization's co-founder. "Quebec has the world-leading system."

The province overhauled its donation rules after the Charbonneau Commission investigated political corruption in Quebec and found that companies and unions were using "straw men" donors to get around spending rules.

But without a scandal, or a leader who promises reform, parties rarely feel prodded to curtail their fundraising, Mr. Conacher said.

Most provinces' financing rules are still looser than those at the federal level, where groups cannot donate and individual contributions to parties are capped at $1,525 a year.

Yukon, Saskatchewan, Newfoundland and Labrador, and Prince Edward Island have no donation ceilings, even for corporations and unions. B.C. has no maximum donation for individuals and groups, provided parties do not accept more than a total of $10,000 in anonymous donations in a given year.

In places that have introduced reforms, corporate and union money has usually been banned, but fairly generous personal caps have been maintained. In Alberta, where the New Democratic government passed a new donation law last summer, individuals are still allowed to give parties up to $30,000 during election cycles, the highest limit in the country. Nova Scotia and Manitoba set their caps at $5,000 and $3,000 respectively.

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Anthony Sayers, a political science professor at the University of Calgary, said donation laws should follow the model of Canadian education and bind the provinces to certain principles while leaving them free to craft their own local policies. The broad precepts that all provinces should adhere to include limits on overall spending, caps on individual donations, and a ban on money from unions and corporations, he said.

Beyond that, he said, "you can imagine variations on the theme." In some provinces, parties require more money to campaign because they have more territory to cover, or need to air ads in different languages. Those regional differences can be seen in the donation returns for the PEI Liberal Party, whose largest contribution in 2014, from a Charlottetown law firm, was just over $7,000, lower than the maximum donation allowed in Ontario.

"There may be some peculiarities to local politics that you might want to take into account," Dr. Sayers said.

Support for public financing to replace big-money donations also varies across the country. In Quebec, a per-vote subsidy for parties is relatively uncontroversial. In Manitoba, the Progressive Conservatives have decried a similar subsidy as a "vote tax" and refused to take it, while promising to revoke the provision if elected. (The federal Conservatives phased out per-vote subsidies when they were in power.)

Dr. Sayers also notes international evidence that public subsidies for parties tend to reduce grassroots fundraising efforts, which can isolate politicians from the electorate.

"I'd be a fan of public funding if it levelled the playing field, but it never does," he said. "It allows parties to disengage from voters."

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While Dr. Sayers supports overhauling political fundraising laws, he argued that doing so is not a silver bullet. Political culture is important in maintaining the system's integrity, he said.

The Nova Scotia NDP was fined for breaking donation rules in 2010 just months after passing them. And in Quebec, widespread political corruption co-existed with the toughest party financing laws in Canada for decades, even before the recent crackdown.

Royce Koop, a political scientist at the University of Manitoba, sees reason for optimism. Although some parties in Canada have opposed per-vote subsidies, he said most have generally continued to raise money from the grassroots while accepting matching funds from the public purse.

Voters in Manitoba have largely come to accept the donation reforms, he said.

"It's not a really hot issue in Manitoba, but at one time it was," Dr. Koop said, "and that's what got us the reforms in this province."