A federal judge has blocked state officials from enforcing most provisions of Proposition 187, citing a threat to public health and concerns over the constitutionality of the illegal immigration initiative.

District Court Judge Mariana Pfaelzer on Wednesday issued a preliminary injunction that bars implementation of Proposition 187 until a trial is held on its legality. But she left intact those provisions making it illegal to sell or use phony immigration documents."This is a great day for the U.S. Constitution, a great day for immigrants, a great day for California," said attorney Peter Schey of the Center for Human Rights and Constitutional Law that was challenging the measure.

Schey spoke to hundreds of supporters gathered outside the downtown Federal Court Building who cheered the the ruling.

Proposition 187, approved in the Nov. 8 election by nearly 59 percent of the voters, sought to halt providing welfare, education and all but non-emergency health care to illegal immigrants. It also requires officials to report suspected illegal immigrants to the Immigration and Naturalization Service.

The day after it was approved, the measure temporarily was stayed pending Wednesday's court hearing.

Pfaelzer's order Wednesday extends that order until trial is completed, citing concerns about the "irreparable harm" to immigrants and the general public.

"The loss of medical services for illegal aliens could result in greater health risks for the general population," Pfaelzer said.

Also, she agreed with arguments by attorneys fighting the measure that federal immigration law does allow protection and services for some immigrants, such as those seeking political asylum or who have family members in the country.

Only the federal government has the authority to determine who can enter and remain in the United States, Pfaelzer said.

Unlike her earlier order, issued the day after the election blocking the law, the injunction can be appealed to a higher court.

Dave Puglia, a spokesman for the Attorney General's Office, said state attorneys will decide later whether to appeal the injunction.

If it is appealed, officials estimated it could take up to one year for the appeal to be heard and an additional one to two years before trial.

"Obviously, what happened today is very, very disappointing," Puglia said.

Pfaelzer said there was clear conflict in the measure with the U.S. Supreme Court's decision in Plyler vs. Doe, the Texas case in which it was ruled that states cannot deny education to illegal immigrants.

But Puglia said the state had hoped she would not include social and health programs in her ruling, since they are separate from educational issues.

A San Francisco Superior Court already had banned the initiative's provisions dealing with education at least until Feb. 28.

Even with Wednesday's order, however, Schey said the state still can enforce existing laws on health and welfare programs in which people were already required to prove that they are legal residents.

"None of that will change," Schey said. "There are not going to be hundreds of thousands of people applying for public assistance because of this ruling."

Some of the most emotional arguments during the hearing came from attorney Stephen Yagman, who said the measure was the result "of a wave of xenophobic hysteria abounding in California.

"This court must stand as a bulwark of principle over paranoia," Yagman said.

Deputy Attorney General Charlton Holland disputed that, saying the measure was aimed only at the cost of state services.

The state also has argued that no ban on the measure should take effect until regulations are drafted as to how it would be enforced.