BRIDGEWATER, N.S. -- Failing to read the fine print on their paperwork could land Ontario gun owners in prison.

Ontario's top gun cop made a major change to the rules regarding restricted firearms in the province - and owners are are taking the government appointee to court.

Legal handgun owners must now carry an "invitation" at all times if they are moving firearms between their homes and provincially approved shooting ranges.

This is an addition to making target-shooters move their guns unloaded, with trigger locks and placed in locked boxes in their vehicles with permits.

Those who don't comply face a minimum three-year sentence.

"(The chief firearms officer) has created a new document that is not specified in the Firearms Act and has bestowed criminal arrest powers on that document," said Tony Bernardo, spokesman for the Canadian Shooting Sports Association (CSSA), one of the groups fighting the change in court. "His job is to administer the law, not to create the law. That's what we supposedly elect politicians to do."

The chief firearms officer said the decision was his to make and gun owners can comply with ease.

"Most of the time, obtaining a written invitation will be easy," chief firearms officer, Ontario Provincial Police Supt. Chris Wyatt, told QMI Agency. "The invitation may simply be a print-out of an e-mail from the member of the host club who has invited the authorization-holder to attend, or it might be a copy of a notice of a competition generated by the host club that invites members of other clubs to attend."

Wyatt said he was "mindful" of the recent killings in Newtown, Conn., when making the change and pointed to the case where an innocent bystander was shot dead outside of a Toronto strip club in January 2008.  The shooter, Edward Paredes, was a restricted firearms owner and carrying his gun with him in the club.

The new conditions appear on the Authorization To Transport (ATT) and advises owners they must be a member of their destined range or an invitee and be able to show police that invitation upon demand.

The federal government will not comment on the issue, saying the matter is before the courts.