Both PMs suggested the ruling overturning Roe v. Wade could result in impacts beyond the United States. Trudeau said: "I want women in Canada to know that we will always stand up for your right to choose." Johnson said the decision "clearly has massive impacts on people's thinking around the world".
French President Emmanuel Macron said: "Abortion is a fundamental right for all women. It must be protected." France is now amending its constitution to ensure abortion rights are maintained.
There are different factors at play, but one appears to be fear of contagion on this and other issues to foreign countries. Liberals and political analysts believe other social changes introduced over recent decades such as same-sex marriage could be targeted.
The Supreme Court move has been cheered on the Republican right of US politics and attacked by US President Joe Biden and other leading Democrats. US states will be able to decide whether or not to introduce bans on abortion services.
Women's rights advocates expressed concern the move could spur on abortion restrictions elsewhere. There was support for the US ruling from the Vatican and in parts of Latin America and Europe. The US joins Poland and Nicaragua as the only countries to have reduced abortion access this century.
In New Zealand, Leader of the Opposition Christopher Luxon felt a statement, saying the status quo on abortion would remain under a National government, was necessary after an MP made a comment on social media. But Luxon's personal views will be a source of scepticism for some activists and voters on whether assurances can be trusted.
Deputy Prime Minister Grant Robertson on Instagram asked Kiwis to call out bigotry and racism.
Leaders of mainstream democracies generally don't want US culture wars to invade their turf. The US has its own political system and culture but its leading position in the world means it can have an outsized impact elsewhere, especially through social media.
Having an internationalist in Biden is an easier, more stable and predictable fit for other countries to deal with compared to former Republican President Donald Trump with his populist "America First" approach.
But feverish domestic debate could distract the US from dealing adequately with the Ukraine war - a key topic of Prime Minister Jacinda Ardern's European trip this week.
Here, abortion has traditionally been a conscience vote for MPs. The majority of the electorate tends to be wary of official intervention in private matters, and the main parties try to straddle the middle.
For the health of New Zealand's democracy, it's better to stay that way.
