Berlin (AFP) - Germany's government has adopted a law requiring mothers to inform their partners if their children were fathered by another man in disputes over support payments.
The measure, dubbed the "milkmen's kids law" in the media, must still pass parliament.
It would apply to cases in which men who believe they are not the biological fathers seek financial compensation in court.
Where there is doubt, women would be required to list all the sexual partners they had around the time the child was conceived.
"We aim to provide more legal security for 'false' fathers to seek recourse," Justice Minister Heiko Maas said.
The measure would allow men who were duped into paying to support a child who was not their own to demand compensation from the biological father for a period of up to two years.
A court would determine the punishment for women who refuse to unmask the actual father, for example a payment of damages to the wronged party.
The legislation allows for exceptions in extreme circumstances, such as when children are born as a result of rape or incest.
Maas began work on the legislation after a federal court ruling in February 2015 said the government needed to put men tricked into believing they were fathers on firmer legal footing.
Estimates vary on how many children grow up thinking the wrong man is their father but German studies put the figure at between less than four percent to more than 10 percent.