Mr.  Fowler, a 35-year-old resident of Traverse City, wants his son to join him in the rite, if the boy wishes.  His ex-wife, Kristin Hanslovsky, objects, saying it could harm her child.

A judge may bar Mr.  Fowler from allowing his son to be given peyote in a case that pits the Constitution's guarantee of religious freedom against a mother's wish to protect her child.

The couple split up soon after their son was born in 1998.  In October 2000, a judge granted Mr.  Fowler custody of his son but prohibited him from giving peyote to the child.  Mr.  Fowler challenged that portion of the decision in the Michigan Court of Appeals, which returned the case to the lower court so it could determine whether peyote use could harm the child.  The next hearing is set for March 21.

Mr.  Fowler, who earns a living by selling food and crafts at powwows, credits his use of peyote with helping him overcome alcoholism and forge a relationship with God.

Peyote, a bitter-tasting cactus that grows in southern Texas and northern Mexico, has been a part of Indian culture for thousands of years.  People who ingest the plant - usually drunk as a tea or eaten as a greenish paste - believe it provides enlightenment and other spiritual and physical benefits.

The plant's active chemical ingredient is mescaline, a hallucinogen.  The U.S.  criminal code classifies peyote as a controlled substance, and in most instances a person caught with more than 4 ounces faces the possibility of a 20-year prison sentence.

But during the last century, peyote's use in religious rites spread among American Indians throughout the United States, including the upper Midwest.  Congress recognized this sacramental use of peyote eight years ago by amending the American Indian Religious Freedom Act of 1978 to protect the practice in all 50 states.

Mr.  Fowler's attorney, Thomas Myers, of Michigan Indian Legal Services, said the case was about ensuring that "rights guaranteed to Native Americans by treaty or statute are secured, and I think that would include constitutional rights."

Martin Holmes, who is representing Ms.  Hanslovsky, did not return a call to his office.  Ms.  Hanslovsky has said she does not want to violate anyone's religious freedom, but that feeding the boy peyote "could cause him harm or long-term neurological defects."

Testifying on Mr.  Fowler's behalf at a court hearing last month, John H.  Halpern, a psychiatrist and researcher at Harvard Medical School, said he has found no evidence of a child or adult being harmed by the use of peyote in Indian religious services.

"This is a sacred ceremony," said Dr.  Halpern, who has conducted an extensive study of peyote use among Indians.  "It's not something to entertain people."

About 300,000 Indians who belong to the Native American Church of North America, the nation's largest church for indigenous peoples, ingest some form of the cactus, he said.

But some members of these types of congregations do not believe children should take the substance.

Anne Zapf, who with her husband runs the Peyote Way Church of God in Klondike, Ariz., feels children should be allowed to attend spiritual ceremonies where peyote is dispensed, but should not ingest it.

At Ms.  Zapf's church, where peyote is used once or twice a year, a person must be at least 18 - or 14, with parental permission - to take it.

"I'm not even into handing peyote to anybody who's under 30 because most people aren't emotionally mature enough or prepared by life enough for the experience," she said.

"Peyote is an introspective experience.  It's a God experience and generally you have to have a few sins under your belt."

• Botany of Peyote (Lophophora williamsii) ()
  The peyote cactus is a flowering plant of the family Cactaceae, which is a group of fleshy, spiny plants found primarily in the dry regions of the New World.