David Leahy, superintendent of the Medicine Hat Catholic Board of Education, said they only became aware in December that the practice has been against the law since 2004.
"Nobody here (at the board currently) was around in 2004," Leahy said in a phone interview.
"That doesn't excuse what happened, but that explains why it happened."
The board went public after the Wildrose party revealed it had learned five board members, including board chairman Peter Grad, attended Premier Alison Redford's Medicine Hat fundraising dinner last Oct. 20 using public money to pay for the $200 tickets.
The news was the latest revelation from the opposition Wildrose and Alberta Liberals.
They have in recent weeks been documenting what they call widespread problems of public officials in schools and municipalities being arm-twisted by the Conservative government to contribute to party coffers in return for preferential treatment or funding.
Chief Electoral Officer Brian Fjeldheim is currently investigating allegations that 10 Conservative riding associations either solicited or received illegal campaign funds.
Party president Bill Smith has promised to co-operate and has asked the other riding associations to go over their books to make sure all donations are above board.
Publicly funded bodies like school boards and municipalities are barred under the Election Finances and Contributions Disclosure Act from contributing to political parties.
Leahy said the board became aware, through media coverage, in mid-December that it was breaking the law.
The practice was stopped immediately, he said.
"The five people who went to the dinner agreed and subsequently have reimbursed the board for the full amount of the tickets," he said.
"Going forward, if representatives from the board decide to attend, they will do so out of their own pocket."
Leahy couldn't say exactly how much money has been donated to the Tories over the years, but said since he took up his post in 2007, board members have been going to premier's dinners in southern Alberta. He says the board goes to the dinners to fulfil its mandate of networking and advocating for students and teachers.
He said in his experience, the Tories have never arm-twisted or even called to advise the premier's dinner was upcoming.
"We only become aware of when the premier's dinner is going to be held when we see advertising (in the newspaper)," he said.
Opposition parties have been putting heat on the Conservatives since CBC-TV reported last fall how municipal politicians in St. Paul had been contributing to the Tories.
On Tuesday, in response to a Wildrose investigation, officials at the University of Lethbridge admitted they had donated more than $10,000 to the Tories after the 2004 ban came into force, saying they, too, didn't know about the law.
That touched off an angry public response from Advanced Education Minister Greg Weadick, who said Thursday that ignorance of the law is no excuse and that public officials have to be aware of contribution rules. His remarks echoed previous comments from Redford.
Both the Liberals and Wildrose have labelled the Tories' response pious hypocrisy, given, they say, that it takes two to transact an illegal donation.
"This is the same old Tory party of 40 years. This is how they hold and maintain power. She (Redford) knows it," said Wildrose deputy leader Paul Hinman.
"When royalty sends out the invitation, you know the behaviour in Alberta. You show up."
Also Friday, Liberal finance critic Hugh MacDonald said he delivered to Fjeldheim's office further evidence of widespread illegal donations to the PCs from municipalities.
"It’s easy for the government to sit on their high horse and tell people not to make illegal contributions, but the fact remains that their party accepted these contributions in the first place," said MacDonald in a news release.
"The government is responsible for setting the tone, and they’ve set a tone that encourages this misuse of taxpayer dollars."
If Fjeldheim does find violations of election rules by any of the 10 PC riding associations he can recommend the Crown lay charges.
Historically, that has not proven effective.
In 2007, former chief electoral officer Lorne Gibson recommended charges in nine cases of illegal fundraising.
Of the nine, the Crown declined to pursue six for lack of evidence and the other three were dropped when the two-year prosecution deadline passed.
Fjeldheim is also by law unable to name the riding associations he is investigating.