A federal judge today dismissed four of nine counts in the trial of former representative Otto E. Passman (D-La.) on charges of bribery, conspiracy, accepting an illegal gratuity and tax evasion.

Acting on a defense motion, U.S. District Court Judge Earl Veron eliminated one bribery count and one illegal gratuity count against Passman, 78. Prosecutors agreed to drop the two other bribery counts.

Passman was indicted a year ago on charges of accepting more than $200,000 from South Korean businessman Tongsun Park in return for pressuring the U.S. and Korean governments into rice sales. Passman also was charged with two counts of tax evasion on the alleged payments from Park.

Although Pas had been charged with accepting three specific payments from Park in 1973-$50,000 in April, $20,000 on June 11 and $28,000 on June 13-Park has testified he made a single payment of $48,000 in June 1973. The payments were the basis for three counts each of bribery and accepting an illegal gratuity, a lesser offense that does not stipulate that Passman was swayed in his offical duties.

Park's testimony combining two of the payments prompted defense motions, and Veron ruled today that the government could prosecute on only on eof the alleged June payments.

Dropping the three bribery counts, the most dramatic development in the case, resulted from the defense's contention that Passman could not he prosecuted twice for the same offense.

Veron gave prosecutors David Scott and Morris Silverstein a choice of the bribery counts or the illegal gratuity counts. They chose the latter, apparently because the level of proof required for conviction is less.

In addition to the two illegal gratuity counts, Passman still faces two counts of income tax evasion and a single counts of conspiracy to defraud the federal government. If convicted on all five, he could be sentenced to 19 years in jail and fined $40,000.

Defense lawyer Cmaille F. Gravel Jr. said outside the courtroom today that the judge's ruling was "a big step in the right direction."

The government's case began to erode with Park's week-long testimony, which was often at variance with previous statements, and was further weakened when Veron refused to allow former representative Richard T. Hanna (D-Calif.) to testify about payments from Park. Hanna is the only current or former congressman convicted in the Korean payments scandal.

The defense was planning to recall Park and more than 20 other witnesses, but after today's ruling Gravel trimmed the witness list and promised to turn the case over to the jury by Saturday.

The defense's first witness, Ralph Waldo Emerson Jones Sr., former president of Grambling State University in northeast Louisiana, testified about his 30-year association with Passman. Jones, a character witness, testified about the former congressman's generosity to the university.

The defense intends to call Louisiana Gov. Edwin Edwards, his brother, Marion Edwards, and rice miller Gordon Dore, who were involved in selling Louisiana's rice reserves.