"The pressure was incredible," said Prentice, recalling his days as a Conservative MP in 2005 when he made it known he would support the controversial bill put forward by the Liberal government.
"(But) there's a duty to balance and protect the rights of everyone."
That humanist rationale, however, didn't cut much ice in his riding of Calgary Centre-North.
There were angry letters to the editor. Staff in his riding office quit. People told him his political career was finished.
One angry Calgarian passed him in a pickup truck, pulled over and threatened to clean his clock on the spot.
Someone set fire to his veranda.
In the church where he was married and his three children were baptized, Prentice and his wife, Karen, arrived one Sunday to learn the sermon was a warning about him.
Nine years later, Prentice, 58, is back in the arena, one of three candidates vying to become the next premier of Alberta as leader of the provincial Progressive Conservatives.
Five decades earlier, his only goal was to play hockey.
Prentice was born on July 20, 1956, in South Porcupine in northern Ontario.
His dad, Eric, was a gold miner and former pro hockey player, a 17-year-old whiz kid winger and the youngest person ever signed by the Toronto Maple Leafs.
Eric was a career minor leaguer, save for five games with Toronto in the bigs in 1943.
As the gold mine dwindled, the family moved in 1969 near a new coal mine in Grande Cache, Alta., and eventually to the mines further south in the Crowsnest Pass.
Through university, for seven summers, young Jim worked in the mines "under the bins."
Coal was dropped by trucks from above into bins and then down onto an underground conveyor belt where Prentice and others — amidst the choking dust, heat, and deafening mechanical din — would pry off the massive rocks that had gotten mixed in with the coal and smash them up.
Hockeywise, Prentice became a top flight winger in his own right, but his promising junior career ended with a devastating knee-on-knee hit.
"I got creamed coming out from behind the net," he said. "That was it."
From then on he focused on university, graduating with a law degree and going to work in Alberta as an entrepreneur and a lawyer dealing mainly with land and property rights.
In the background there was politics. Always politics.
From age 20, he worked for the federal and provincial Conservative parties, taking a page, he said, from his parents' involvement in their community.
Save for one failed bid for elected office provincially in 1986, he stayed in the backrooms as an organizer and bean counter. He had an agreement with Karen, he said, not to get into the all-consuming life of politics until their kids were much older.
When he did run again, in 2002, the federal conservative movement was a mess, fractured between the PCs and the Canadian Alliance.
Prentice urged reunification and in 2002 stepped aside as the PC candidate in Calgary Southwest so that then-Alliance leader Stephen Harper could run unopposed to represent the centre-right.
In 2004, at age 47, he finally grabbed the brass ring, winning the Calgary riding for the newly merged Conservative Party.
In 2006, Harper won a minority government and Prentice was in cabinet. Over the following six-plus years he was given high marks for his work in diverse portfolios — Indian and northern affairs, industry and environment.
He was considered Harper's right-hand man, running the powerful cabinet operations committee, helping pull the levers at the very centre of national power.
Now he will try to become Alberta premier and take over a provincial PC party fractured and demoralized by infighting and flat-lining poll numbers.
To take them back to the top, he will apply the lessons from under the bins.
"I always said I got my education there," he said.
"I learned teamwork, I learned respect for other people. I learned the fact that the smartest guy in the room is often not the guy you think is the smartest guy.
"Everybody's got something to contribute and everybody's got to be part of the solution."
Also on HuffPost