NEW YORK — NEW YORK (AP) — Subjecting a sex offender who is no longer imprisoned to “extraordinarily invasive” penile stimulation testing risks violating the premise that even convicts retain their humanity, a federal appeals court said Thursday.

The ruling by the 2nd U.S. Circuit Court of Appeals in Manhattan frees former police officer David McLaurin of a requirement that he submit to penile plethysmography [penile stimulation test], a test in which a man’s erectile responses are measured as he is shown sexually stimulating images. An all-male three-judge appeals panel said it saw a “clear distinction” between penis measurement and other conditions of supervised release, including restrictions on where sex offenders may live, their interactions with children and their access to pornographic material.

“But we see no reasonable connection between fluctuating penis size and public protection — certainly none strong enough to survive the careful scrutiny that we give to unusual or severe conditions of supervised release,” the court wrote of the conditions imposed after someone completes a prison sentence. “A person, even if convicted of a crime, retains his humanity.”

McLaurin, 48, challenged the requirement after a Vermont judge sentenced him to 15 months in prison, to be followed by a treatment program that could include the testing, because McLaurin failed to fill out paperwork required by sex offenders. McLaurin had notified authorities that he would be working as a chef at a Putney, Vt., inn in 2011, but he later lost the ob and went to the Birmingham, Ala., area, where he was arrested. He was returned to Vermont to face charges and was released from prison in November.

He was required to register as a sex offender because he was convicted more than a decade ago of producing child pornography for photographing a topless 13-year-old girl who told authorities she had requested a photo shoot to help her modeling career, the court said.

A Vermont federal judge who concluded McLaurin was “unlikely to reoffend again” had said it was “standard” to include a test in which a man’s erectile responses are measured as he is shown sexually stimulating images.

The appeals panel said the government had cited instances when Vermont judges had ordered the procedure, but the court added that judges in New York and Connecticut within the 2nd Circuit had not recently imposed such conditions and that the probation office in Vermont has ceased recommending it.

The appeals court said it seemed “odd” to try to deter someone from committing sex crimes by showing him depictions of sex.

“We hold that this extraordinarily invasive condition is unjustified, is not reasonably related to the statutory goals of sentencing, and violates McLaurin’s right to substantive due process,” it said. The court found the testing “is unduly intrusive and bears insufficient relation to correctional or medical treatment, the protection of the public or deterrence of a crime.”

McLaurin’s public defender, Steven L. Barth, said he was pleased with the ruling.

“Mr. McLaurin and the Federal Defender Office felt strongly that the invasive plethysmograph testing condition was unwarranted and unconstitutional,” he said.

Prosecutors did not immediately respond to a message for comment.

The appeals court did not hide its skepticism about the two- to three-hour test, in which a man’s penis is attached to a pressure-sensitive device known as a plethysmograph. The apparatus measures minute changes in blood flow and erection size as the subject views pornographic images or videos.

The judges flatly rejected government arguments that the procedure amounted to “treatment” for sex offenders, saying prosecutors offered no evidence “that this exceedingly intrusive procedure has any therapeutic benefit, and none is apparent to us.”

It cited a ruling similar to its own by the 9th U.S. Circuit Court of Appeals in San Francisco that found the test’s accuracy and reliability “have been severely questioned.”

The 2nd Circuit said even if the test were accurate, “the goal of correctional treatment during supervised release is properly directed at conduct, not at daydreaming.”

The procedure “inflicts the obviously substantial humiliation of having the size and rigidity of one’s penis measured and monitored by the government under the threat of incarceration for a failure to fully cooperate,” the 2nd Circuit judges wrote.

As the court noted, the procedure was developed by Czech psychiatrist Kurt Freund as a means to study sexual deviance and it was at one time used by the Czech government to identify and “cure” homosexuals.

The court wrote: “Whether the device was ‘successful’ in this regard is not reflected in the record.”