Alabama Governor Kay Ivey has signed into law legislation that would require certain sex offenders to be chemically castrated before their parole.
Governor Ivey's press office said that she had signed the bill, which is to take effect later this year.
The measure applies to sex offenders convicted of certain crimes involving children younger than 13.
Chemical castration involves injection of medication that blocks testosterone production.
Under the measure, certain offenders must receive the medication before they are paroled from prison. A judge would decide when the medication could be stopped.
Seven other states and US territories - California, Florida, Guam, Iowa, Louisiana, Montana and Wisconsin - have authorised chemical castration, but it's unclear how often it's used.
Some legal groups have raised concerns about use of forced medication.
.'It certainly presents serious issues about involuntary medical treatment, informed consent, the right to privacy, and cruel and unusual punishment. And, it is a return, if you will, to the dark ages,' Randall Marshall, the executive director of the Alabama chapter of the American Civil Liberties Union, told CNN in a statement.
The move follows Alabama's adoption of one of the country's most stringent abortion laws.
The legislation makes performing an abortion at any stage of pregnancy a felony punishable by up to 99 years or life in prison.
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