One night three years ago, soon after the city threatened to outlaw them, the locks were sawed off the Pont des Arts.

WSJ: Couples Adorn Bridges With Weighty Tokens of the Heart

"It's very touchy to attack the phenomenon because it draws tourists, " says Joel Retailleau, a city official in the 6th arrondissement, where the Pont des Arts is located.

WSJ: Couples Adorn Bridges With Weighty Tokens of the Heart