PHOENIX - The nation's high court will decide three - and likely four - Arizona disputes in its new session, which begins today.

Two hearings are scheduled for next month, one involving a spat between the Tohono O'odham Nation and the U.S. government, the other to decide the legality of state tax credits to help children attend private and parochial schools.

In December, the justices will review a three-year-old law that lets state judges decide if Arizona firms have knowingly hired undocumented workers and, if so, to suspend their licenses or put them out of business.

And the court has all but decided to review the matching-funds provision of the state's law on public financing of elections. Justices already have indicated they have a problem with a federal appeals court ruling declaring the funding legal: The justices let stand a ban on matching funds for the current election, changing the rules in the middle of the campaign.

Potentially the most controversial - and significant - is the challenge of what has become known as the employer-sanctions law.

The measure is Arizona's attempt to dry up the supply of jobs as a way of deterring illegal immigration.

The Immigration Reform and Control Act, approved by Congress in 1986, precludes states and cities from imposing any civil or criminal penalties on companies for hiring illegal immigrants. But the same law allows states to have their own "licensing or similar laws."

The state law, formally known as the Legal Arizona Worker Act, seeks to fit that exception by going after all state licenses. Both a trial judge and the 9th U.S. Circuit Court of Appeals agreed.

Business groups, joined by some civil rights organizations, said that's misreading the law.

The newest justice, Elena Kagan, won't participate in this hearing because the Justice Department filed its own objection to the Arizona law while she was still solicitor general.

If the justices say the employer-sanctions law is pre-empted by federal statutes, that likely means the demise of SB 1070, which gives police more power to detain and arrest illegal immigrants. A federal judge already placed key provisions on hold, saying they likely run afoul of federal law.

The tax-credit case involves a 1997 law allowing Arizonans to get a dollar-for-dollar offset from what they owe the state in income taxes for money they donate to organizations that provide scholarships for private and parochial schools.

Individuals have been able to divert up to $500 a year, and couples double that. A bill signed earlier this year by Gov. Jan Brewer will allow that to be adjusted annually for inflation.

Another case Kagan has recused herself from is the dispute between the Tohono O'odham Nation and the federal government.

By law, the government manages the nation's lands and holds income derived from that land in trust. That includes income from the sale of natural resources as well as leases.

The lawsuit contends the United States handled $2.1 billion in transactions for the nation between 1972 and 1992 and "has never fulfilled its duty to provide a true and adequate accounting" of the trust funds. It also alleges "gross mismanagement" by the federal government.

But the issue before the high court isn't the merits of the case. It's the question of whether the tribe, which brought a similar action in a different case and in a different court, can pursue this one.

A federal appeals court said the two cases are sufficiently different, as one seeks an accounting and the other seeks specific monetary damages.

The last Arizona case is one in which the high court has, at this point, agreed only to consider legal briefs.

A 1998 law allows candidates for statewide and legislative office to obtain public funds if they agree not to solicit private donations. It also provides a dollar-for-dollar match if their privately funded foes spend more.

Challengers, all running with private money, said that limits their free-speech rights because it deters them from spending more knowing it means more for their publicly financed opponents. They also said donors won't give them money if they know it also helps their foes.

In an order earlier this year, the high court upheld a restraining order issued by a federal judge in Phoenix barring the matching funds. But the justices have not formally decided if they will review a federal appeals court decision finding the matching funds constitutional.