U.S. District Judge John G. Koeltl did not immediately rule after hearing arguments today from lawyers for the city, bat makers and school baseball sponsors.

The law, set to take effect Sept. 1, would ban metal bats in high school games. It resulted from claims that today's metal bats cause balls to go farther and faster, heightening the risk of injuries.

Koeltl told David A. Ettinger, a lawyer for those challenging the law, that he thought the safety issues covered in the litigation were the kind normally reserved for legislators.

In April, the City Council overrode a mayoral veto of the legislation; the lawsuit then was filed.

During several hours of arguments today, Koeltl was told the law resulted from legislators seeking to balance the need for safety with the desire of young athletes to have the higher batting averages that some people believe result from metal bats.

"Aren't those the kinds of choices we leave to legislators?" Koeltl asked Ettinger. "Those are the kinds of lines that depend on policy choices."

Ettinger said legislators needed to provide some scientific evidence that the metal bats are unsafe. Manufacturers then could adjust the makeup of metal bats to make them safer than some wooden bats, he said.

To dramatize his argument, Ettinger held up five baseball bats, including a bat made from the wood of a maple tree. He said the maple bat had become popular among some major leaguers, including Barry Bonds, because it hits the ball harder than some metal bats.

Ettinger said if the City Council merely were choosing bats according to which ones would never cause injury, the city would outlaw everything except plastic bats, though he noted those bats would rarely get a ball back to the pitcher.

Jerald Horowitz, a lawyer for the city, said the city needed no more than a rational basis or common sense reasons for the bat ban.

"This court should not second guess what the City Council has decided and act as a super legislature, as many (prior) courts have pointed out."