Federal law expressly prohibits illegal immigrants from working in the United States. That is undisputed. 

What's not as certain is whether under state laws, those same illegal workers can collect back pay and compensation benefits if they get hurt on the job.

In short, it depends on what state they are in.

The Supreme Court on Monday passed up an opportunity to hear arguments about one such dispute and presumably settle the conflict within the states.

The issue of back pay to illegals has come up in at least a dozen states with mixed results.

Judges in Louisiana, Pennsylvania, Georgia and Minnesota have issued rulings saying that illegals are entitled to collect on their benefits claims because state laws don't expressly prevent illegals from doing so.

Meanwhile judges in other states including Virginia, Michigan and Nevada have tossed out these claims, saying the Immigration Reform and Control Act of 1986 passed by Congress prohibits illegals from collecting benefits for work they should never have been allowed to perform.

A Louisiana business claimed there's no way it should be forced to pay workers' compensation to a Mexican who was never supposed to be working in the first place.

Antonio Rodriguez was injured while doing some roofing work at the University of Louisiana-Lafayette. He was a subcontractor and under Louisiana law people can make workers' compensation claims to what is known as their "statutory" employer. That means Vaughan Roofing & Sheet Metal is the on the hook for injury claims by people, like Rodriguez, it didn't directly hire and didn't know was an illegal immigrant.

Vaughn Roofing fought the claim saying federal immigration laws should preempt Louisiana, or any other state, from allowing illegals to collect workers' compensation. A Louisiana appellate court noted that it was "undisputed" that Rodriguez wasn't supposed to be working but cited a similar case siding with the illegal worker that concluded "there is no express statutory provision (in Louisiana) excluding undocumented workers from workers' compensation coverage."

Kirk Landry, the roofing company's lawyer, said in his Supreme Court petition that the Louisiana court's logic is "particularly problematic" because of the federal immigration policy. He asked the high court to hear the case to resolve "an inconsistent and haphazard approach to analyzing issues of constitutional law and federal statutory interpretation."

The court as is custom did not explain why it didn't take the case. It is unusual for the justices to take cases that do not involve conflicting rulings from federal appellate courts or state disputes that directly involve constitutional protections.

In 2005, the justices also declined to hear a similar case from Georgia.