People accused of driving under the influence of alcohol generally are not entitled to jury trials, a unanimous Supreme Court ruled Monday.

The court, in a case from Nevada, said states are not required to hold jury trials for drunken driving when the maximum jail terms are six months and other penalties are not particularly severe.The court left open the possibility the Constitution might require a jury trial in the case of a repeat offender who could be sentenced to more than six months in jail if convicted of driving under the influence more than once.

In another case, the court turned down an appeal by northeastern states seeking to force the federal government to crack down on acid rain and other pollution they say is caused by smokestacks in other states.

The court, without comment, refused to order the federal Environmental Protection Agency to take steps to limit interstate air pollution.

The justices rejected an appeal by two Nevada men, Melvin R. Blanton and Mark D. Fraley, who said the penalties for being convicted of driving under the influence (DUI) are serious enough to warrant jury trials.

Lawyers for the two said Nevada is one of only five states that does not permit jury trials in such cases. They listed the other states as Louisiana, Mississippi, New Jersey and New Mexico.

While there is mounting national concern over the seriousness of drunken driving, Justice Thurgood Marshall said for the court Monday that Nevada classifies driving under the influence as a petty crime.

The demarcation line for petty crimes is a maximum sentence of six month in jail, Marshall said. The fact that Nevada prescribes other penalties does not raise the offense to a serious crime, he said.

Blanton was arrested in North Las Vegas on July 18, 1986, and Fraley was arrested in the same town on June 29, 1986. Blanton has not been tried. Fraley was convicted and was sentenced to two days in jail and fined $310.

The Nevada Supreme Court ruled in 1987 that they were not entitled to jury trials. The state court said jury trials would place an expensive burden on the municipal court system.

In other action, the court:

- Agreed to review the stiff fines imposed against four Yonkers, N.Y., councilmen for defying a federal judge's order to adopt a housing desegregation plan.

- Said federal workers do not have a right to sue in federal court when they accuse the union representing them of unfair treatment.

- Agreed to decide whether prison inmates are entitled to a court hearing and other safeguards before being forced to take anti-psychotic drugs.

- Barred a lawsuit against a former federal prosecutor who refused police protection to a witness gunned down before she could testify.

- Turned down the free-speech arguments of a financial magazine accused of violating an anti-touting provision of federal securities law.