Some lawyers are scoffing at the legal justification provided by Alberta Justice Minister Jonathan Denis for limiting the release of information about illegal political donations to only three years.

"If my interpretation is correct, then I would say that the minister is obfuscating as opposed to clarifying the issue as to why the information cannot be brought forward beyond three years," said Robbie Davidson, one of Alberta’s top criminal defence lawyers and a highly regarded expert in the law.

On Thursday, the Progressive Conservative government of Premier Alison Redford pushed through Bill 7, which amends the province’s Election Finances and Contributions Disclosure Act.

Despite sharp criticism from opposition parties, the new legislation only allows the chief electoral officer to release information about proven illegal political donations which occurred after Jan. 1, 2010.

That effectively means information about dozens of cases of illegal donations, including one involving the premier’s sister, Lynn Redford, will never be made public.

Outside the legislature, Denis told CBC News he had no legal choice but to impose a three-year limit.

"We're going back as far as we can, with the three years," Denis said. "If we were to go beyond that particular time, there's a section of the Charter that prohibits imposing past offences today."

Lawyers say laws cited by Denis don't apply to information disclosure

Denis specifically cited Section 11(g) of the Canadian Charter of Rights and Freedoms.

It states: "Any person charged with an offence has the right not to be found guilty on account of any act or omission unless, at the time of the act or omission, it constituted an offence under Canadian or international law or was criminal according to the general principles of law recognized by the community of nations."

CBC News asked D’Arcy DePoe, another top defence lawyer and president of the Criminal Trial Lawyers’ Association, whether he believes the charter section cited by Denis is applicable.

"It has nothing to do with the circumstances of disclosing previous illegal campaign donations," DePoe said. "The three-year limit is simply an arbitrary date that has been picked. It has nothing to do with the charter.

"In a plain reading of the section, any lawyer should be able to tell you that it has no application," DePoe said. "He is a lawyer. I think he is using this for an obvious political reason, and it is not proper."

Denis also cited Section 52(3) of the Election Finances and Contributions Disclosure Act. It says a person can only be charged criminally with an offence within three years of committing the offence.

But, like that charter section cited by Denis, this section has nothing to with public disclosure of information about cases in which the chief electoral officer finds an illegal donation has been made.

Ministers claimed law to keep information secret requested by chief electoral officer

Bill 7 was based in part on recommendations for amendments made by Chief Electoral Officer Brian Fjeldheim. Those recommendations say nothing about imposing a three-year limit on information disclosure.

It has been illegal in Alberta since 2004 for any publicly funded institution to make political donations.

An ongoing CBC News investigation, begun in 2011, has uncovered widespread illegal donations - almost exclusively to the ruling Tory party - by municipalities, post-secondary institutions, school boards and even government departments dating back to 2004.

Fjeldheim has so far opened more than 80 files and issued a penalty in 48. But he released no specific information about the illegal donors because he was barred by law, a law passed in June 2010 by Alison Redford when she was justice minister.

When the opposition raised the issue in the legislature in May, both Denis, and Deputy Minister Thomas Lukaszuk, claimed the law to keep the information secret was enacted at the request of former chief electoral officer Lorne Gibson.

But both Gibson and Fjeldheim contradicted the Tory ministers, saying their office would never seek to keep such information from the public.