Union lawyer Gwen Gray said the high court's unanimous decision to throw out the law shows how restrictive it is.
"The union is very pleased with the Supreme Court ruling. It has been a long court battle," Gray said in an interview.
"It is a very important decision for not just trade unions, but any kind of public organization or people's organization."
The United Food and Commercial Workers local representing employees at the Palace Casino at West Edmonton Mall was involved in a 305-day strike in 2006.
The union posted signs near the picket line saying images of people crossing the line might be posted on a website.
Several people cited Alberta's Personal Information Protection Act in their complaints to the provincial information and privacy commissioner.
The commissioner appointed an adjudicator, who ruled that the union had violated the act.
But a court found that the ruling violated the union's rights and the Alberta Court of Appeal granted the union a constitutional exemption from the act.
The Supreme Court, in a 9-0 ruling, essentially agreed, but also threw out the whole law. It has given the province a year to make appropriate changes.
Alberta Justice Minister Jonathan Denis said the government is considering how best to respond to the high court ruling.
"Alberta remains committed to providing strong privacy protection for our citizens, including individual Alberta workers," Denis said is a statement.
"We will look at the legislation and make sure we strike an appropriate balance that will comply with the ruling of the court while still maintaining strong protection for all Albertans.”
A Justice Department official said the law would be amended to change the provisions that apply to unions and picketing, but he said other parts of the privacy law would also be changed. The official said it is too soon to say what those other changes would be.
Amendments to the law won't be introduced until next year.
Jill Clayton, Alberta's privacy commissioner, also said any changes the province makes to the law would likely focus on unions and picketing.
She said it is too early to say what kind of specific changes are needed.
"We will be writing to the government to provide some input and some suggestions about how government might deal with amendments and we will certainly be encouraging them to move quickly on it," she said.
In the meantime, she said it would be business as usual.
"Other kinds of activities that PIPA (the privacy law) protects and regulates, PIPA will continue to protect and regulate."
Gray said privacy laws are needed but they shouldn't restrict the ability of unions or anyone else to freely communicate about public or political events.
The union hopes the Alberta government will bring in a new privacy law that would be limited to commercial activity, she said.
"If that was the case, the union's picket line conduct would not be subject to the privacy law," she said.
"That is the way it is federally and in every other province in Canada. That is what we would like the government of Alberta to do."
The high court justices stressed the basic importance of freedom of expression in the context of labour disputes. They said Alberta's privacy law imposed restrictions on the union's ability to communicate and promote its case during a legal strike.
Justices Rosalie Abella and Thomas Cromwell, writing for the court, said the privacy act does address important issues and seeks to give people a measure of control over personal information.
"The price (the act) exacts, however, is disproportionate to the benefits it promotes," they wrote.
They said Alberta's privacy act is overly broad.
"(The act) imposes restrictions on a union’s ability to communicate and persuade the public of its cause, impairing its ability to use one of its most effective bargaining strategies in the course of a lawful strike."
During their arguments before the court, both the privacy commissioner and the provincial attorney general had said that if they lost the case, they would prefer to see the whole law struck down.
"We agree," Abella and Cromwell wrote.
The Alberta Federation of Labour congratulated the UFCW, calling the Supreme Court ruling a major victory for the rights of workers.
"This ruling ensures freedom of expression for working people and their unions," federation president Gil McGowan said. "It's a win for the rights of unions to fully represent workers during labour disputes."
— With files from The Canadian Press Ottawa
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