PHOENIX — Saying the state has done all it needs, a federal judge on Friday threw out a 21-year-old lawsuit over what Arizona does to ensure that all students have an opportunity to learn English.

On the surface, the ruling by Judge Raner Collins rejects the contention by challengers that it is not enough for the state to offer special four-hour ``immersion'' courses for students who are not proficient. Collins said that model for teaching meets the requirements of federal education laws.

But the decision also voids a 2000 ruling by another federal judge who concluded that Arizona was not meeting its obligations under the Equal Education Opportunity Act. That law requires states to ensure all students have an opportunity to learn, an opportunity that specifically requires states to take ``appropriate action'' to help them become proficient in English.

That leaves no legal path for those who continue to contend that the entire scheme by the state to provide instruction to ``English language learners'' is legally insufficient.

Attorney Tim Hogan, who represents parents who filed the initial lawsuit in 1992, said he is studying the ruling and has not decided whether to appeal.

Central to the case is that federal law.

In the wake of that 2000 ruling, lawmakers have tinkered with the funding formula which gives schools extra money to aid those who need extra help in learning English. Each time, however, the court rejected it as not providing the cash is adequate to do the job.

In 2009, however, the U.S. Supreme Court said Collins overstepped his authority.

The justices said Collins took testimony of how well students were performing in Nogales, where the lawsuit originated, and then ordered Arizona to do more statewide. The high court sent the case back to Collins, telling him his orders cannot stand unless he gets evidence of statewide violations.

The current state plan sets up teaching ``models'' for all schools to follow. That includes putting affected students into separate classes for four hours a day where the only thing taught is English.

Among Hogan's charges were that these separate classes amount to unlawful segregation.

But Collins, in Friday's ruling, said he never proved that the state's implementation of the four-hour classes ``was driven by a deliberate intent to discriminate on the basis of race, color or national origin.'' The judge said federal law leaves it to state or local authorities whether to do ``immersion'' programs like this or ``bilingual'' programs where students learning English remain in regular classes that are taught in both languages.

``In light of the evidence presented, the court finds that the structured English immersion method and the four-hour model are valid educational theories,'' Collins wrote.