U.S. District Court Judge Robert L. Taylor ruled today that the code of ethics for Maryland state officials promulgated by Gov. Marvin Mandel in 1969 applied equally to the governor.

Mandel had maintained since his indictment on political corruption charges 20 months ago that the code did not apply to him as one of the top four elected state officials.

The question of just who was covered by the code, which Mandel testified yesterday was designed to assure citizens "that no state officer . . . can be improperly influenced," came up today during Mandel's cross-examination by the chief prosecutor.

Central to the prosecution's case is the assertion that Mandel was improperly influenced by accepting gifts from friends and then conducting state business in such a way as to benefit those same friends financially.

Out of the hearing of the jury, Mandel's attorney, Arnold M. Weiner, asked Judge Taylor to "instruct the jury cleraly that the code does not apply to the governor, but is merely a guide . . .

"I believe it is the court's duty," Weiner said, "to hold that it does not apply to the governor, and I think that's . . ."

At that point Taylor interrupted, "I think it does," the judge said abruptly, "I think it does. It's a standard of conduct for him as well as all other citizens to look to in the performance . . . I think it does apply to him. Yes sir, I don't have any serious doubt as to that."

"Is the court so holding?" asked Weiner.

Yes sir, I'm so holding. I am so holding," said the judge, apparently settling for the moment the question of whether the governor was subject to his won code of ethics.

The question of whether the code of ethics applied to the govenor had come up before. Even before the first trial, which was halted followin attempts to tamper with the jury, the then-presiding U.S. District Court Judge Herbert F. Murray had ruled that the question was a technical one, which he chose to sidestep.

What was important, Murray said, was that the jury in the Mandel corruption tiral could look to it as a "standard of conduct" and determine for themselves what relevancy, if any, it had on the intent of the governor and his codefendants.

Weiner had argued that even though Mandel devised the code, the code had been mandated by the legislature. The legislature did not have the power to require that Mandel's code apply to the governor, whose office is coequal with the legislative branch.