The 5-to-3 decision appeared to endorse vigorous state efforts to punish employers who intentionally hire illegal workers. The majority opinion, written by Chief Justice John G. Roberts on behalf of the court’s five more conservative members, said that Colorado, Mississippi, Missouri, Pennsylvania, South Carolina, Tennessee, Virginia and West Virginia had recently enacted laws similar to the one at issue in the case.
The decision did not directly address a more recent Arizona law that gives the police greater authority to check the immigration status of people they stop.
The United States Court of Appeals for the Ninth Circuit blocked enforcement of that law in April, and the case may reach the Supreme Court soon.
The challenge to the Arizona law that was the subject of Thursday’s decision was brought by a coalition of business and civil liberties groups, with support from the Obama administration.
They said the law in question, the Legal Arizona Workers Act, conflicted with federal immigration policy.
The act was signed into law in 2007 by Janet Napolitano, a Democrat who was then the state’s governor. Ms. Napolitano is now secretary of the Department of Homeland Security.
The decision on Thursday turned mostly on the meaning of a provision of a 1986 federal law, the Immigration Reform and Control Act, which said that it overrode “any state or local law imposing civil or criminal sanctions (other than through licensing and similar laws) upon those who” recruit or hire “unauthorized aliens.”
The question was whether Arizona was entitled to supplement the penalties in the 1986 federal law with much tougher ones of its own. The state argued that the phrase in parentheses — “other than through licensing and similar laws” — allowed it to suspend or revoke the business licenses of repeat offenders. Critics called that provision of the state law a “business death penalty.”
Chief Justice Roberts wrote that the word “licensing” should be read broadly to allow states to supplement federal efforts to prevent the hiring of illegal workers. His decision was joined by Justices Antonin Scalia, Anthony M. Kennedy, Samuel A. Alito Jr. and, for the most part, Clarence Thomas.
Peter J. Spiro, who teaches immigration law at Temple University, said the majority’s broad reading would be consequential. “In some ways, this becomes an exception through which states can drive a truck,” he said. “It’s definitely going to embolden anti-immigration constituencies to work through state capitals.”
There is reason to think that those constituencies will meet with some success, judging from the fact that 13 states filed a brief supporting Arizona.
But Robin S. Conrad, a lawyer with the U.S. Chamber of Commerce’s litigation unit, said in a statement that “the decision does not give states or local governments a blank check to pass any and every immigration law” and that only state laws consistent with the federal one were permissible. The Chamber of Commerce was a plaintiff in the suit.
Ms. Conrad added that “businesses from Main Street to Wall Street are overwhelmed by a cacophony of conflicting state and local immigration legislation” and that Congress should bring order to the area.
Cecillia D. Wang, a lawyer with the American Civil Liberties Union’s Immigrants’ Rights Project, also urged a cautious reading of the decision, saying that it was narrowly tied to the Arizona law. The A.C.L.U. was part of the odd-bedfellows coalition that had challenged the law.
Jay Sekulow, a lawyer with the American Center for Law and Justice, a conservative public interest law firm that filed a brief urging the court to uphold the law, said the ruling was “a victory for Arizona and other states” that “provides a realistic roadmap” for enacting legislation that does not run afoul of the federal law.
Justice Stephen G. Breyer, in a dissent joined by Justice Ruth Bader Ginsburg, said the word “licensing” in the federal law should be read narrowly to mean “employment-related licensing systems” and not all licenses. “Why not an auto licensing law?” he asked of the majority’s interpretation. “Why not a dog licensing law?”
Chief Justice Roberts responded that Congress could easily have limited the phrase had it wanted to. “If we are asking questions,” he added, “a more telling one may be why, if Congress had intended such limited exceptions to its prohibition on state sanctions, it did not simply say so, instead of excepting ‘licensing and similar laws’ generally?”
Chief Justice Roberts wrote that the Arizona law was a measured response to real problems and that “licensing sanctions are imposed only when an employer’s conduct fully justifies them.”
He added that there was no reason to fear that the state law would lead to discrimination against Hispanics who were in the United States lawfully.
“The most rational path for employers,” the chief justice wrote, “is to obey the law — both the law barring the employment of unauthorized aliens and the law prohibiting discrimination — and there is no reason to suppose that Arizona employers will choose not to do so.”
But Justice Breyer said the state law disrupted a carefully calculated balance between competing Congressional goals and that it “seriously threatens the federal act’s antidiscrimination objectives.” The state law increased penalties for hiring illegal workers, he said, but it left “the other side of the punishment balance — the antidiscrimination side — unchanged.”
The decision, Chamber of Commerce v. Whiting, No. 09-115, also upheld a second aspect of the Arizona law, this one making mandatory an otherwise voluntary federal program, E-Verify, that allows employers to validate whether potential employees are authorized to work.
In his dissent, Justice Breyer said it was a mistake to require use of a “pilot program” that was “prone to error.”
Justice Sonia Sotomayor wrote a separate dissent. Justice Elena Kagan recused herself from the case because she had worked on it as United States solicitor general.
“I cannot believe,” she wrote, “that Congress intended for the 50 states and countless localities to implement their own distinct enforcement and adjudication procedures for deciding whether employers have employed unauthorized aliens.”