SALT LAKE CITY — A special session of the Utah Legislature looms on the horizon as Gov. Gary Herbert asked Wednesday for modifications to a voluntary employment verification bill before its July 1 implementation date.

Herbert released a statement on the deadline day for bill signing, expressing concern that SB251, which would require Utah businesses that employ 15 or more people to screen employees for the legal right to work, is not clearly voluntary.

While the current language of the bill mandates use of E-Verify or another federal screening program by companies, it does not have an attached penalty for failure to do so. In debate of the bill during the 2010 legislative session, lawmakers agreed that the de facto result was a voluntary program. But Herbert wants to eliminate any ambiguity on the issue.

"This bill achieves some very important goals, such as protecting young Utahns against identity theft," Herbert said. "My intent is simply to clarify that Utah's businesses are not mandated to participate in the E-Verify program."

Herbert said he heard from many factions on the possible effects of SB251, including members of Utah's minority and business communities. Lane Beattie, president of the Salt Lake Chamber, said the clarification will help quell concerns raised by chamber members.

"This issue was of particular concern to the business community," Beattie said. "The inclusion of the word 'voluntary' would alleviate the fears of small-business owners and allow dialogue on this important issue to continue."

The bill's sponsor, Sen. Chris Buttars, R-West Jordan, told Herbert he's willing to discuss the legislation and consider the changes.

Only the governor has the power to call the Legislature into special session and then create the agenda for that proceeding.

Herbert also confirmed on Wednesday that, as promised, he will allow a new tobacco tax to become law without his signature.

Herbert said the decision was based on his ongoing opposition to tax increases of any kind, but he acknowledged the necessity of finding a middle ground with the state's lawmaking body.

"While I remain opposed to any increase in taxes this year, I recognize that the give-and-take of the legislative process requires negotiation," Herbert said. "And I have found it necessary to accept the Legislature's proposal in order to protect education funding in Utah."

The new tax puts some $43 million into state coffers and helped offset cuts to this year's education budget.

Herbert's work on Wednesday also included vetoing a proposal that would have removed the necessity of a test for those seeking a notary public credential. Herbert said testing ensures that notaries understand their responsibilities and duties and that eliminating the requirement would not serve the people of Utah well.

Herbert's office did not provide details on a possible date for the special session or what other business may be considered by lawmakers at that time.