The measure outlawed metal bats under the theory that they produce balls with greater velocity and raise the risk of injury because of less reaction time. Opponents, including Little League Baseball and equipment suppliers, say there is no evidence metal bats are more dangerous.

Youth leagues and lawmakers are proposing similar bans in other areas, including New Jersey, where a 12-year-old boy went into cardiac arrest and suffered serious injuries after a batted ball struck him in the chest.

In New York City, Mayor Michael Bloomberg vetoed the bat ban this month, saying the issue should be left up to those who run the youth leagues, not the government. But the City Council overwhelmingly knocked down the veto by a vote of 41-4.

"What we're trying to do is reduce risk," said Councilman James Oddo, the sponsor of the bill.

Opponents argue that there is no scientific evidence proving metal bats pose a greater danger than wood bats and that the anti-metal movement relies on emotional anecdotes over data.

Shortly after the council's vote, a group of opponents announced plans to file a federal lawsuit seeking to block the ban.

Donald Douglas, director of the Public Schools Athletic League, joined the suit and said in a statement that baseball "is safe and thriving a generation after metal bats were introduced." He said there was "no compelling reason to make a change."

Little League president Stephen D. Keener, who was not part of the suit, issued a statement saying the organization is "disappointed in the action taken today by the New York City Council to override the logic and sensibility of Mayor Bloomberg's veto."

In 2005, an American Legion Baseball study found no substantial scientific proof to support the argument that wooden bats are safer than metal bats.