Judge Brian Bruser found Curtis Schaefer, 38, not guilty in Yellowknife territorial court on April 27.
Bruser accepted the defence argument that Schaefer honestly believed the trap was legal.
It had been given to his father about 20 years ago as part of a government test of new trapping technology.
Schaefer was also found not guilty of contravening trapping regulations by possessing an animal caught with the trap.
Defence lawyer Kelly Payne of Yellowknife said her client had no reason to think the trap was illegal.
Payne said Schaefer had taken reasonable steps to keep himself informed on trapping regulations.
"He actively tried to seek out information," she said. "He fulfills the defence of due diligence."
She said he was never told by government that the trap was illegal, and no such information was available at trapping courses offered by the hunters and trappers association.
When the trap went missing from his trapline, Schaefer called the Resources, Wildlife and Economic Development department to report it missing and learned that wildlife officers had seized it.
Schaefer's father, Chief James Schaefer of Salt River First Nation, testified he received the trap about 20 years ago from a wildlife officer as part of a test of quick kill technology.
In 2004, Curtis Schaefer took the trap down from where it had been hanging for years and caught a wolverine.
Schaefer says he's glad the court case is over. "It's certainly a weight off a person's mind."
However, he says the relationship between Aboriginal people and RWED - now known as the Department of Environment and Natural Resources - has to become better, explaining the department sometimes deals with matters in a heavy-handed way.
The issue of the illegal trap could have been dealt with over a cup of coffee, he noted.
"I have always tried to conform with regulations as they come up," Schaefer added.