OKLAHOMA CITY (AP) _ Legislation that would authorize microchip implants in people convicted of violent crimes was sent back to a committee for more work Wednesday after state House members questioned whether the proposal would violate constitutional civil liberties.

The measure, approved by the Senate, authorizes microchip implants for persons convicted of one or more of 19 violent offenses who have to serve at least 85 percent of their sentence, including murder, rape and some forms of robbery and burglary, while prohibiting government from requiring microchips implants in anyone else.

The tiny electronic implants are commonly used to keep track of pets and livestock, but several House members questioned whether their forced use in people would be unconstitutionally invasive.

``We are going down that slippery slope,'' said Rep. Ed Cannaday, D-Porum.

Lawmakers never voted on the measure. During debate, its author, Rep. Sue Tibbs, R-Tulsa, asked that it be sent back to a joint House-Senate conference committee where the exception for violent offenders was inserted.

Cannaday and others said the measure may violate the Fourth, Fifth And Fourteenth amendments to the U.S. Constitution. The Fourth Amendment prohibits unreasonable searches and seizures, the Eighth Amendment prohibits cruel and unusual punishment and the Fourteenth Amendment contains the Due Process and Equal Protection clauses.

``I see it as invasive,'' Cannaday said. He said many sex offenders and prisoners convicted of other crimes are already required to wear wrist or ankle bracelets when they are released from prison so their movements can be monitored by satellite tracking devices.

``I think implanting a chip is more invasive than wearing a bracelet,'' Cannaday said.

``I'm concerned about the precedent this establishes,'' said Rep. John Wright, R-Broken Arrow. ``Apparently we're going to permanently put the mark on these people.''

Wright and Rep. Mike Reynolds, R-Oklahoma City, said they removed their names as co-authors of the legislation over their concerns.

Rep. Mark McCullough, R-Sapulpa, said microchip technology would help manage violent criminals once they are released from prison.

``It is difficult to know what in the world to do with these individuals,'' McCullough said. ``We walk on a slippery slope every day in what we do here.''

``We're talking about criminals of the worst kind,'' Tibbs said.

She said implant technology has been used in other states but was unaware if any state authorized implantation of microchips against a person's will.

``It's just a teeny, tiny thing,'' Tibbs said. She said the microchips are not permanent and can be easily deactivated or removed.