MONTGOMERY (AP) — Alabama lawmakers approved legislation that would require certain sex offenders to be chemically castrated before being released on parole.

Lawmakers gave final approval to the bill last week and sent it to Gov. Kay Ivey.

The bill by Rep. Steve Hurst applies to sex offenders who committed crimes involving children younger than 13.

Chemical castration involves the injection of a medication that blocks testosterone production. Under the bill, the offenders must receive the medication before parole. A judge would decide when they could stop.

Hurst has proposed the measure for more than a decade.

Randall Marshall of the ACLU of Alabama said there are constitutional concerns with the requirement.

A spokeswoman for Ivey said Tuesday the bill is undergoing a legal review before the governor decides whether to sign it.