VISTA -- The American Civil Liberties Union of San Diego and Imperial Counties will ask a judge to stop Vista from releasing the names, addresses and phone numbers of private individuals who have registered with the city as day-labor employers, an attorney with the group said Thursday.

The ACLU's legal director, David Blair-Loy, said he would file a class action complaint today in Superior Court on behalf of four anonymous employers to block the release of the information, which has been requested by a local anti-illegal immigration activist.

"This is just one of those cases where, I think, the right to privacy prevails over the right of public disclosure," Blair-Loy said.

The city was sent a copy of the complaint Thursday, Blair-Loy said.

City Attorney Darold Pieper said Thursday afternoon that the city will appear at a hearing about the matter -- most likely to take place Monday. He declined to comment on what position the city will take.

Barring the court's intervention, however, Pieper said the city would have to release the list of employers by the end of business Monday.

This latest legal action was prompted by a public records request filed with the city on June 28 by Mike Spencer, the leader of an anti-illegal immigration group called the Vista Citizens Brigade.

Members of the brigade sometimes protest against the hiring of day laborers at a shopping center in central Vista where several men gather waiting for work. Spencer and his group have alleged that many of the mostly Latino workers are in the country illegally.

Spencer asked the city for the list of employers who have so far registered to hire day laborers, according to a preliminary copy of the ACLU's complaint. The list has 111 names on it, city officials have said.

Blair-Loy said he feared the personal information of registrants could be used as a tool for harassment by those who say that day-labor hiring promotes illegal immigration.

"Frankly, no matter who made this request, I'd be filing this case," Blair-Loy said. "But the fear of harassment just makes it more pressing."

Spencer said Thursday that posting the information on the Internet or using it to harass employers "was not my intent at all."

"I thought it would be interesting just to see if my request would set in motion any sort of action and see what the result would be," Spencer said.

The ACLU already has an extensive legal history with Vista's hiring law, which requires people who hire temporary workers off the street to register with the city, display permits in their car window and present workers with written terms of employment.

The ordinance also states that information submitted to the city by prospective employers will be available as public record.

Last year, the organization joined forces with California Rural Legal Assistance Inc. to sue the city in an attempt to stop the law from being enforced.

The parties reached a settlement in that case last month, which stipulated that the hiring law would remain in effect while Vista made some changes to the way it is enforced.

Among other things, the settlement stipulated that Vista would not immediately release the names and contact information of registered employers, but -- if it received such a request -- would wait 10 days to give the employer's attorney time to seek a court order.

Spencer said he was curious to see what actions the court and city would take.

"Does the city have a right to bargain away my rights to public information?" he asked.

Contact staff writer Craig TenBroeck at (760) 631-6621 or ctenbroeck@nctimes.com.