The law hasn't caught up yet to the way politics gets done in the 21st century. But Bill C-76 — the Liberal government's new package of changes to federal election laws — could be a small step toward regulating the "permanent campaign" that took over Canadian public life in the past decade.

Whether it does will depend in part on whether the bill can outlive a constitutional challenge.

With the Election Modernization Act, the Liberal government proposes to regulate political advertising during a new pre-writ period that would begin on June 30 in years with a fixed election date.

Between June 30 and the start of the official campaign period, political parties would be limited under the new law to spending $1.5 million on advertising. So-called 'third-party organizations' would see their ad spending capped at $1 million.

Acting Democratic Reform Minister Scott Brison lay out some of the proposed changes in a new bill tabled on Monday 1:29

It's that limit on third parties — advocacy organizations and groups that come together to run political campaigns — that's most likely to be challenged in court.

Similar legislation in Ontario is being fought by a coalition of trade unions arguing their charter rights to free expression and association are being curbed. And pre-election rules in British Columbia have been struck down twice already — in 2009, after a challenge by unions, and then in 2012, after a reference by the B.C. government.

At issue here is what the Supreme Court once described as the "egalitarian model" of Canadian elections — the "level playing field" that regulations on election spending are supposed to maintain.

"You basically can't have an egalitarian model unless you restrict pre-writ speech," said Michael Pal, a law professor at the University of Ottawa who has written about how the permanent campaign threatens the established political system and advised the Ontario government on its legislation.

The field has changed

Federal spending limits for political parties have been in place since 1974, but only during the official campaign period — between when Parliament is dissolved and a new vote is held.

Successive attempts to regulate third-party spending during federal campaigns were struck down in court until, in 2004, the Supreme Court ruled against a challenge mounted by Stephen Harper, the future prime minister, who was then president of the National Citizens Coalition.

In that case, the court found the restrictions on third-party advertising did infringe on the right to freedom of expression, but that the infringement was justified.

"In the absence of spending limits," the majority wrote in a 6-3 ruling, "it is possible for the affluent or a number of persons pooling their resources and acting in concert to dominate the political discourse, depriving their opponents of a reasonable opportunity to speak and be heard, and undermining the voter's ability to be adequately informed of all views."

Since then, the focus of concern has shifted to the unlimited spending that political parties and third parties can do between elections.

Blessed with significant financial resources — and with an unstable minority in the House of Commons — the Conservatives bought waves of television ads targeting Liberal leaders Stéphane Dion and Michael Ignateiff ahead of the 2008 and 2011 elections.

The Liberals, with their anemic fundraising operation, were unable to respond in kind. And those ads were widely credited with driving the Liberal losses that followed.

The 'level playing field' seemed to be threatened by the emergence of a permanent campaign — by the fact that the sort of activity normally associated with election campaigns was no longer limited to the five-week period immediately preceding a vote.

A fixed election date allowed political actors to better plan their inter-campaign activities. Third-party groups emerged as a potentially significant force in advance of the fixed election date in 2015 — until Harper's move to launch an early campaign forced them to operate under official limits.

All that set the stage for what the Liberals are proposing now: a cap on campaign lengths and a new pre-election period that would limit the ability of political actors to flood the airwaves in the weeks immediately before a campaign.

A 'cautious' attempt at reform

If the Liberal changes end up surviving a court challenge, it might be because the government is taking a relatively light touch.

"They were actually quite cautious, from a constitutional point of view. Maybe more than I would have even thought they had to be," Pal said.

A million dollars could still buy a lot of pre-campaign political activity. And while third-party groups would be limited under the new law in how much they can spend on ads that promote or oppose a party or candidate, the bill makes an exception for advertising that merely focuses on an "issue."

Acting Democratic Institutions Minister Scott Brison discusses the new rules and powers being given to the chief electoral officer. 0:41

Under Canada's system, governments can fall unexpectedly and Parliament can be dissolved on a whim. That makes it difficult to legislate a strict period between elections. But Pal suggested the pre-election period could be extended to cover a full year ahead of a fixed election date, as is already the rule in the United Kingdom.

In Ontario, the pre-election period is six months. New Brunswick has gone even further, requiring that political parties stay within an annual limit for spending on advertising.

The further a government reaches, the more likely it is to encounter pushback. But the way we do politics in Canada has been evolving — and that could encourage both governments and the courts to go further than they might have considered going in the past.

"We started with restrictions in the campaign period. Now we've got a pre-writ limit," Pal said. "And if that is held to be constitutional, which I think it should be, then there'll be a chance to expand it down the road."