Former D.C. Superior Court judge Charles W. Halleck, testifying as a defense witness at the bribery trial of his former judicial colleague, Robert H. Campbell, told a jury yesterday that he (Halleck) routinely decided against imposing any fines in cases involving overweight truck tickets because he thought the law was being enforced unfairly.

Halleck, whose controversial 12-year career on the bench here ended in 1977, testified in U.S. District Court that he thought that only truck drivers were ticketed by District police and said no one had ever demonstrated to his satisfaction that overweight trucks were harmful to city streets.

During cross-examination by Assistant U.S. Attorney Carol E. Bruce, Halleck acknowledged that he got his information from his conversations over the years with police officers, from reading about disputes involving trucks and highways and from his own experiences as a traffic court judge.

"In the panoply of criminal offenses, they [overweight trucks] ranked right at the bottom," Halleck testified.

Halleck's testimony came in the trial of former judge Campbell on charges that he accepted more than $10,000 in cash, goods and services in exchange for his favorable treatment of overweight truck tickets issued to Excavation Construction Inc., a Bladensburg firm.

Halleck's testimony bore on the defense contention that Campbell's action in suspending the imposition or execution of sentences in overweight truck ticket cases was no different from decisions reached by other judges of Superior Court.

Campbell's defense lawyer, R. Kenneth Mundy, also told the jury at the outset of the case that he would present evidence to show that Campbell's decisions in those cases may have been influenced by the fact that he thought police were unfairly ticketing black truck drivers.

Former judge Campbell, Larry A. Campbell (no relation to the judge), the general manager of Excavation Construction, and the firm itself are on trial for bribery, conspiracy and racketeering.

The defense also called as a witness yesterday U.S. District Judge Harold H. Greene, former chief judge of Superior Court, to testify about how he decided which of the court's 44 judges would be assigned to hear various types of cases including those bought up in traffic court.

Greene testified that traffic court was considered an undesirable assignment by judges because the legal issues were not challenging, the caseload was heavy and the atmosphere was "somewhat chaotic."

The government has contended that the construction company knew in advance when Campbell would be assigned to traffic court and kept its tickets until they could be brought before him. Greene testified that judges got five to seven days' advance notice before their next assignments were announced publicly. When he was asked by defense lawyer Mundy if former judge Campbell was effective in moving and reducing the traffic court calendar, Greene responded, "Certainly."

The prosecution formally completed presentation of its evidence yesterday.

Judge Thomas A. Flannery, who has presided over the trial, yesterday denied motions from all defense lawyers that their clients be acquitted by the court because the government's evidence was insufficient.