Among the many bad ideas tossed around as New York considers pot legalization is a push to ban the city Administration for Children’s Services from considering parental marijuana use.

To be clear, ACS doesn’t remotely take kids from their home simply because mom or dad tests positive. But clear abuse of any drug — including alcohol, which is completely legal — is an issue that social workers are duty-bound to look at.

Bronx Borough President Rubén Diaz Jr. suggests otherwise, asserting in a new report that ACS breaks families apart simply because “a new parent” tests positive for pot.

In fact, any problem seems to rest more with public hospitals that (much more often than private ones, Diaz claims) routinely drug-test mothers of newborns and report positives to ACS.

Diaz wants hospitals prohibited from testing new mothers for pot without their consent. But rather than trying to dictate new state laws, he should be assailing the policy-setters at NYC Health + Hospitals.

Nor should a social-justice agenda put babies at risk: Heavy pot use, like excessive drinking, can lead to serious prenatal problems — impacting brain development and leading to premature birth and/or low birth weight. The federal Centers for Disease Control advise against weed use during pregnancy and warn that babies can be exposed to THC through breast milk.

New York’s debate over legalizing pot is already complicated enough without tossing phony issues into the mix. It takes more than a single positive test to trigger an ACS investigation, and more than pot use to bring a child-removal petition.

ACS has far better things to do than create bogus reasons to seize kids. And it doesn’t need its hands tied by politicians looking to invent a campaign issue.