The National Labor Relations Board which had been reviewing the strike by union school bus drivers and matrons in New York City said on Friday that the strike is legal.
The Board rejected a complaint by a group of 20 private bus companies who argued that they were caught in a dispute between the union and the city.
The strike does not violate the National Labor Relations Act because the union has a primary labor dispute with the employers, according to the NLRB.
The Board says it prohibits unions from striking secondary employers in order to pressure the employer with whom they have a dispute.
More than 8,000 drivers and matrons of yellow school buses in New York City went on strike Jan. 16 leaving more than 150,000 students to find alternative transportation.
Members of Amalgamated Transit Workers Union Local 1181 are striking over job protection after the City put the school bus contract up for bid.
"We spend $6,500 per student per year. Since 1979, no administration has re-bid this contract. They do not want another company to come in, under bid and they might or might not have the same workers. They want us to guarantee that anyone who comes in gives them the same jobs at the same salary at the same seniority. We've had 12 judges rule that's illegal," said Mayor Michael Bloomberg.