Is swinging legal?
Yes — private consensual sex between adults is legal across the US, Canada, the UK, and most of Western Europe, and that includes swinging. What can be regulated is the venue: many cities license off-premise lifestyle clubs but not on-premise (where sex happens at the venue), and some jurisdictions restrict alcohol sales at clubs that allow nudity. Specific exposed-in-public-place rules apply in most places. The activity itself, between consenting adults in private, is legal everywhere it is practiced openly.