Chief Justice John Roberts (photo via Flickr).

The main argument centered around Arizona's state immigration law conflicting with federal immigration laws. The court concluded that federal law doesn't stop the state of Arizona from revoking business licenses from those who do not follow state law.

From POLITICO:

Chief Justice John Roberts wrote in the majority opinion that the court had come to its decision because “the state’s licensing provisions fall squarely within the federal statute’s savings clause and that the Arizona regulation does not otherwise conflict with federal law.”

The three dissenting judges were Stephen Breyer, Ruth Bader Ginsburg and Sonya Sotomayor, all liberal judges. The fourth liberal judge on the bench, Elena Kagan, recused herself from the case as she was solicitor general under the Obama administration before being appointed to the court.

The Desert Sun reported:

Breyer said the Arizona law upsets a balance in federal law between dissuading employers from hiring illegal workers and ensuring that people are not discriminated against because they may speak with an accent or look like they might be immigrants.

Employers "will hesitate to hire those they fear will turn out to lack the right to work in the United States," he said.

Business interests and civil liberties groups challenged the law, backed by the Obama administration.

The measure was signed into law in 2007 by Democrat Janet Napolitano, then the governor of Arizona and now the administration's Homeland Security secretary.

The holding also upheld part of the Arizona law that made using E-Verify, a program that allows employers to verify whether potential employees can legally work, mandatory instead of voluntary.

From The New York Times:

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 was recused from the case because she had worked on it as United States solicitor general.

“I cannot believe,” Justice Sotomayor 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.”

View the full ruling here.