The sponsor of a bill that would prevent Utahns from changing the sex listed on their birth certificates on Wednesday unveiled revisions that he couched as a "workable resolution" to controversy surrounding the proposal.

The updated legislation, HB153, would still set in stone the sex placed on someone’s birth certificate. But now, it would allow state residents to list a different gender identity on their driver licenses.

"This substitute bill reflects input from various interested parties and provides a workable resolution of the issues presented," Rep. Merrill Nelson, who's sponsoring the legislation, said in a news release. "Those who assert a different gender identity from the sex on their birth certificate are free to designate that identity on their driver license, which is used as the most common form of personal identification."

The changes also strike Nelson’s original gender definitions — females as individuals with ovaries who have anatomy for “providing eggs and receiving sperm from a male donor” and males as individuals with testes who have anatomy for “delivering sperm to a female recipient.”

The news release states that the substitute legislation, slated for a Thursday committee hearing, preserves the idea that individuals are born either male or female. At the same time, the revisions recognize a difference between sex and gender identity, the release stated.

However, Troy Williams, executive director of Equality Utah, called the legislation a “callous attack” on transgender Utahns.

“It denies them equal protection and violates their right to privacy,” Williams wrote in a statement. “If this bill passes we will see boycotts of Utah, including sports teams, concerts and conventions canceling. Businesses may opt out of opening new offices here. This bill harms the trans community and may also harm our state.”

Nelson’s substitute bill limits the possible sex designation on a birth certification — the only options would be “male,” “female” or “undetermined.” People would only be able to change their birth certificates to correct a “mistake of fact” that happened when they were born or to change their gender designation from “undetermined” to “male” or “female,” according to the bill language.

Individuals would be able to seek a driver license or identification card with a different sex if they submit a notarized statement that they are not embroiled in a court case or proposing the gender designation to avoid creditors or to perpetrate fraud, among other things.

Nelson, R-Grantsville, did not return a call requesting comment on the changes.

In the past, he has said he’s advancing the measure based on “the scientific and medical fact that an individual’s sex is determined at conception by chromosomal make-up and is not subject to change or self-determination later in life.”

His proposal has been widely criticized by LGBT groups and the ACLU of Utah, which as labeled it as unconstitutional.

The state’s existing law for a person wanting to make a legal change to match their gender identity is ambiguous and under review of the Utah Supreme Court. Currently, government agencies have applied their own, and often inconsistent, interpretations, and judges have pinballed between granting and denying requests.

Nelson has said his proposal has nothing to do with beliefs espoused by the The Church of Jesus Christ of Latter-day Saints. However, the measure does follow close on the heels of a speech in which one of the faith’s top leaders, Dallin H. Oaks, said “gender is eternal” and members should resist pressures to “make changes that confuse or alter gender or homogenize the differences between men and women.”