In a significant shift, the United Federation of Teachers earlier this month formally resolved to explore sponsoring a charter school in New York City. This has been discussed for years, but, in a little-noticed development, the UFT has just made it official.

This has the potential to be an illuminating experiment in more ways than one. If the school turns out to be excellent, it could be an argument for the union against the critics who see the UFT as part of the problem in New York City’s schools. A successful UFT charter school could even be a sign that Mayor Bloomberg should pay more attention to the UFT’s complaints about his education policies.

A success could also transform the union’s own attitude toward charter schools. The union has often perceived such schools — which are tuition-free, are largely government-funded, and are free of many of the rules imposed by the central city education bureaucracy — as a threat. If the UFT school gets off the ground and is a success, the union could recognize that charter schools are an opportunity.

If the UFT charter is less than a success, it might also serve the purpose of making the union a little more understanding of the challenges faced by management in public schools. It will be something to see the grievance procedure at the UFT’s charter school.

By far the most important element of this development is that it signals movement toward a landscape in which parents have a choice whether to send their children to a school that is run by the principles of the teachers’ union or one that is run by other principles. The more choices available to parents, and the more competition that arises, the better, as far as we are concerned. As it is, many of New York’s public schools aren’t run according to the principles of either labor or management, but under the uneasy and imperfect compromise represented by the contract between the city and its teachers, on which negotiations seem to be going nowhere.

The teachers’ union and its president, Randi Weingarten, have our congratulations for having taken this bold and important step in beginning to seek a charter for a new school. Mr. Bloomberg, Schools Chancellor Klein, and the backers of the New York charter schools law before them have our congratulations for creating the environment in which the UFT is starting to be maneuvered into being just one choice available to parents, rather than the default monopoly.