A House Judiciary subcommittee on Thursday approved legislation that would give satellite TV providers a leg up in their longrunning battle with cable companies.

The bill would prevent states from taxing satellite, cable and Internet television services differently. It is sponsored by full committee Chairman John Conyers Jr., D-Mich., and was approved by the Commercial and Administrative Law Subcommittee by voice vote.

Satellite firms DirecTV and EchoStar sought unsuccessfully last fall to attach the tax language to legislation extending the Internet access tax moratorium for another seven years. Although the language did not stick to that vehicle, it caught Conyers’ eye and he introduced a standalone bill on the topic.

Satellite TV operators are fighting what they call “discriminatory” sales taxes in a handful of states that impose a higher levy on their services than on cable television services. In Ohio, for example, satellite subscribers pay a 5.5 percent tax on their service, while cable customers pay nothing, the satellite TV firms said.

DirecTV and EchoStar brought the tax battle to Congress because they have been losing in statehouses, where they are typically outgunned by cable lobbyists, and in the courts, where they have sought protection under the commerce clause of the Constitution with mixed results.

Cable operators and many states say the higher satellite sales tax is reasonable because satellite TV providers don’t pay the local franchise fees that cable companies are charged for laying lines along public rights of way. DirecTV and EchoStar are exempt from those fees because they beam programming directly to customers from their satellite constellations — without having to dig along streets or hang wires from utility poles.