Was it?

My memory is that gay marriage was declared unconstitutional by the Ontario Court of Appeal in July 2003. The Chrétien government of the time chose not to appeal it and instead referred a draft bill to the Supreme Court of Canada to ask them to issue a binding ruling. The government (now the Paul Martin government?) did slow things down by adding a fourth question to the referral, which even the Supreme Court called out as political bullshit. Once they came back (in late 2004) affirming that same-sex marriage needed to be legal, there was a lot of talk about using the notwithstanding clause as the only possible option to ignore their ruling. Ultimately, though, the bill legalizing gay marriage federally passed in February of 2005.

I remember in the debates during the subsequent election that Paul Martin accused Stephen Harper of planning to reverse it. Harper rolled his eyes and said that he considered the matter settled (since I think even a lot of Conservative voters were fine with it by then). Martin then promised to remove the NWC from the charter if reelected. He was not.