A Prince George's County circuit court judge yesterday upheld the finding of a hearing examiner that county executive Lawrence Hogan violated county labor laws in his handling of labor negotiations with the county's 1,500-member public employes union.

Judge Jacob S. Levin ruled that evidence presented to him supported the finding that Hogan's veto of a tentative agreement with the union because of political considerations constituted as unfair labor practice.

Levin ruled that Hogan must now sign the tentative agreement and send it to the county council for final approval. Under the terms of the agreement, county workers would receive a 4.7 percent pay increase, retroactive from the year ending June 30, and a cash bonus. It also provides for a 5 percent increase for the current fiscal year.

In his ruling last March the hearing examiner, Hugh Jascourt, found that Hogan had improperly undercut the authority of his own negotiators and tried to force the union to criticize his political opponents as a condition for signing the contract.

Besides ordering Hogan to sign the agreement, Jascourt also had ordered him to publicly post notices to county employes that the county never again will bargain in bad faith. In his ruling yesterday, Levin upheld that order as well.

Levin's decision was a severe setback to Hogan, who long as maintained that Jascourt was biased in favor of the union because of a job he held as legal council of AFSCME International 12 years ago.

Hogan was attending the Republican National Convention in Detroit yesterday and was unavailable for comment. Court Attorney Robert Ostrom said, "at this stage of the game the balll is now thrown across the net [to the union]. We are 15-love."

Ostrom said he had "an obligation to recommend an appeal [of Levin's ruling] to the state court of special appeals."

For the union, which felt the county's progressive labor code and collective bargaining in general were challenged, the decision also was significant. Members of the union have been without a contract a cost-of-living raise granted all other county employes for over a year.

Ernie Crofoot, state representative for AFSCME, said, "We're elated at this decision. The county has tried to thwart the law at every turn and this decision slaps at Hogan's arrogance in power. We hope he doesn't try to drag this out further; if he does, it will make clear his intention to oppress people merely for being organized into unions."

If Hogan decides against going to the court of special appeals, Levin's decision will resolve a battle between the county and the union over a new contract that began in February 1979 and exploded amidst much hostility last February.

At that time, it appeared that a settlement had been reached when negotiators for the union signed a tentative agreement that was considered to be favorable to the county.

However, when the contract was presented to Hogan for his final approval, he blew up and refused to sign it, saying "a strike is sometimes good politics," according to county officials familiar with the incident.

What angered Hogan was not the contract, which he maintains he had not read at that point, but statements by political adversaries on the county council that criticized his handling of the negotiations.

According to one of Hogan's labor negotiators who testified before Jascourt last March, Hogan said he would not approve the contract because his political opponents on the council and the union were joining forces to help a future challenger to Hogan's reelection in 1982. The negotiator who gave that testimony since has been moved out of the labor office to another county job.

This sequence of events is what led to Jascourt's findings last March and Judge Levin's decision yesterday.

After Hogan vetoed the tentative agreement, the union immediately filed an unfair labor practice charge against him for bargaining in bad faith and impulsively "pulling out the rug" from under negotiators he had appointed to make decisions in his behalf.

Hogan continually has maintained he vetoed the agreement because of several new provisions he did not like. At the time he vetoed the agreement Hogan said several minor economic provisions relating to health benefits and other matters were unacceptable. Later he said he vetoed the agreement because it allowed too many county-paid benefits for union leaders.