Unfamiliar with that part of Shuswap Lake, Todd Kerr misread a navigational beacon on Copper Island, believing it was on the northern tip of the eastern shore of Blind Bay.

That critical mistake on a dark night on Aug. 2, 2008, resulted in a 26-knot (48 km/h) collision with the island that killed Pattie McKenna and seriously injured others aboard a powerboat Kerr was piloting.

As Kerr’s trial on criminal charges of dangerous driving causing death and injury ended Wednesday, the decision facing B.C. Supreme Court Justice Robert Powers is clearly a difficult one, said Crown prosecutor Neil Flanagan.

“Did the standard of care fall markedly below the standard of care that would be exercised by a reasonably prudent operator?” Flanagan asked, attempting to define the crux of the case. “Your decision has profound implications for everyone with an interest in the trial.”

That includes Kerr, who faces criminalization and a possible jail sentence if found guilty, and McKenna’s mother, who has attended the trial.

“It includes the thousands of people who use Shuswap Lake and all citizens who care about justice and the rule of law,” Flanagan said.

In his closing submissions, Flanagan argued that a mistake of fact is not necessarily a legitimate defence in such a case. Even if the judge finds Kerr misread the beacons, what the experienced boater did with that information fell short of the standard of care, he said.

“This is a case where common sense dictates a certain course of action. . . . Shuswap Lake is not beyond the pale. It’s a place down the road where hundreds, thousands of people go. Speed is clearly set out in the regulations and dictated by common sense. When you set out in a boat at night and you can’t see past your nose, you go slow. It’s not any more complex than that.”

He maintained that a planing speed of 26 knots — when a boat is travelling at 41 feet per second — was not a safe speed under marine conditions that Kerr understood.

Responding to the Crown’s position, defence counsel James Sutherland acknowledged his client made a mistake but argued that doesn’t constitute a marked departure. Boating, like driving a vehicle, is inherently risky, he argued.

“We don’t penalize someone because one of those inherent risks actually happened,” Sutherland said.

He questioned why Copper Island has only one beacon, but the judge cautioned him that many marine hazards are left unmarked.

“It is a curious marking,” Sutherland conceded.

Kerr acted responsibly by accompanying his friend, boat owner Jason Baird, that night, he said. He engaged in sound reasoning of the hazards.

“What makes this short of a marked departure is that he did exercise caution,” Sutherland said. Kerr may have been going too fast, but he had only his eyes to rely on.

“It was a horrendous mistake, just nothing more than a mistake.”

Powers reserved his decision until August or possibly September.