Aereo, a startup venture that recently began offering live television broadcasts online to New York City customers, won an important legal reprieve on Wednesday as a U.S. District Court judge denied the request of five major broadcasters for a preliminary injunction that would have shut down the Aereo service pending the outcome of a jury trial. Backed by media mogul Barry Diller and a host of other investors, Aereo provides customers with access to live television programs through an array of thousands of thumb-size antennas that are assigned to individual customers and that retransmit broadcast signals over the Internet to subscriber iPhones, laptop PCs and other mobile devices. Although the service is presently confined to the New York City market, Aereo officials hope to expand the offering nationwide, provided that the court’s final ruling is favorable. Shortly after Aereo announced its plans last winter, five broadcast networks serving the New York City area—ABC, CBS, Fox, NBC and a unit of Univision Communications—filed suit on grounds that the Aereo service violates copyright law and illegally retransmits broadcast programming without consent. Although U.S. District Court Judge Allison Nathan agreed with the broadcasters’ claim that the Aereo service is capable of causing irreparable harm to their business models, she refused to grant injunctive relief, concluding the plaintiffs had failed to show that “the balance of hardships decidedly tips in their favor.” Although the broadcasters offered no comment, Diller remarked in an e-mail statement: “I did think we were on the side of the angels in this project.”