WASHINGTON -- A participant in the bruising American battle over voting rights warns that Canada is treading on dangerous ground with its proposed electoral reforms.

One of the lawyers who helped strike down the voter ID law in Pennsylvania last month says legislation tabled by the Harper government will inevitably wind up depriving some people of their voting rights.

That's why any change to voting requirements should be made with the strictest care, in the spirit of achieving more accurate election results, said Witold Walczak, legal director of the American Civil Liberties Union for Pennsylvania.

That warning comes from a country where voting rights are an especially emotional subject, for obvious historical reasons. Americans know the issue well. And the impact of ID rules has been studied extensively, re-emerging in recent years as a hotly debated partisan issue.

Multiple academic studies point to an impact on turnout, especially among specific demographic groups: the young, the poor, and minorities.

The measured statistical effect has ranged from a couple of percentage points to more than a dozen, depending on what the study's measuring, what state it's looking at and the state's ID requirement.

The new rules envisioned in Ottawa are not nearly as cumbersome as the ones struck down in Pennsylvania. The right to a ballot there hinged on a document from the state Department of Transportation, and the ability to get that document required ID that some voters simply couldn't obtain.

The Canadian bill would still allow 39 types of ID. People could still vote with one government-issued card that includes a photo and home address, or with two other documents like a bank statement and utility bill.

If passed, however, the legislation would end the practice of one voter vouching for another's identity. It would also prohibit the use of voter information cards as proof of identity.

Walczak said Canadians need to ask themselves an important question: Will the number of cases of fraud prevented by these changes actually be greater than the number of people prevented from voting?

Because, he said, there will certainly be some of the latter.

"They're going to show up on election day -- having every right to vote, meeting all of your constitutional requirements, but not knowing that they have to bring an ID," Walczak said in an interview.

"They show up, they wait in line, they get to the front and hear, 'Sorry, you can't vote, you've gotta go home.' And then that person says, 'Ah, screw it, I don't have time."'

In Pennsylvania, Walczak said, the government has failed to point to a single case of identity fraud at the polling station -- which is the only kind of fraud that a voter ID rule would address anyway, he added.

In Canada, chief electoral officer Marc Mayrand has said the end of vouching would affect more than 100,000 voters. He said it would affect young people who move around a lot, aboriginals with no formal papers proving their on-reserve address, and elderly people who have just moved into retirement homes.

In the U.S., the issue carries historical overtones.

After the Civil War and the end of slavery, African-Americans actually did have the right to vote everywhere in the country. A number of black congressmen were even elected in the South.

But that right was gradually stolen, and suppressed for nearly a century, as different states adopted measures like poll taxes and literacy tests aimed at restricting the black vote. The 1965 Voting Rights Act, signed by Lyndon Johnson, was an attempt to remedy that with federal oversight of states' voting standards.

Parts of that law were struck down last year by the Supreme Court. Now, as it stands, 34 U.S. states already have some type of voter ID law, and the introduction of these laws has intensified since the Supreme Court ruling.

Using politically loaded language, in reference to the Jim Crow era, Attorney General Eric Holder has called these new voter ID laws a "poll tax."

Here's what some studies say about their impact:

--Researchers at the universities of Washington, Mexico and Northern Arizona concluded that white voters in Indiana were 12 per cent more likely than blacks to have the proper ID, and Republicans were 15 per cent more likely to have it than Democrats.

--In a national study, researchers at the University of Chicago and Washington University in St. Louis concluded that black youth were 22 per cent more likely than whites to be asked to show ID, and that 13 per cent more black youth said their lack of adequate ID kept them from voting.

--Statistics guru Nate Silver estimated in 2012 that voter ID laws would reduce turnout by 2.4 per cent in Pennsylvania and help Republicans by 1.2 per cent. He predicted a similar pattern in Kansas, and lesser echoes in Idaho, Tennessee, Oklahoma, Rhode Island and Utah.

Republicans have called these measures a question of fairness, and of protecting the integrity of the voting system. But one party official veered wildly off-script, and was fired after sharing his politically incorrect thoughts in public.

North Carolina Republican precinct captain Don Yelton conceded that there had only been one or two cases of fraud in his county of 60,000 voters -- but, he said, the new rules would have another type of impact.

"The law is gonna kick the Democrats in the butt," he told a comedian-interviewer from the Daily Show.

"If it hurts a bunch of college kids that's too lazy to get up off their bump and go get a photo ID, so be it. If it hurts the whites, so be it. If it hurts a bunch of lazy blacks that want the government to give them everything, so be it."

The Canadian government will not say a word about the American debate. In fact, multiple inquiries into whether it bothered consulting the U.S. data -- or drew any inspiration from it -- met with non-responses.

Several phone calls and emails to minister Pierre Poilievre's office, asking specifically about those American studies, produced a 429-word written reply that did not include a single reference to the U.S.

"When drafting the legislation, the minister was very fortunate to have such a wealth of information from our electoral agency," said an email from his office.

That email referred to a report for Elections Canada that said there were irregularities in 25 per cent of cases involving vouching in the 2011 election. Irregularities do not necessarily equal fraud, the report notes.

"There is almost no evidence of fraud in U.S. elections," said David Lublin, a political-science professor at American University. He's an expert in U.S. elections and Southern politics, and he also knows Canadian politics well.

"The real question here should be, 'What is the problem? And is the solution being proposed by the Conservative government appropriate to the problem?"'