Sometimes being the underdog has its advantages. But it's certainly been an uphill battle for digital TV startup Aereo as it faced a federal lawsuit brought on by the major TV broadcast networks. Now, the U.S. Justice Department is taking sides in the legal fight -- and not with the scrappy startup.

In a Supreme Court filing yesterday, the Justice Department said it is officially backing the broadcasters in their quest to shut Aereo's streaming service down. It argues that New York City-based Aereo -- a service that uses antennas to capture broadcast signals and make them available to paying users on any type of internet-connected device -- infringes on broadcasters’ copyrights. It requests that a lower court’s decision supporting Aereo be overturned.

The TV broadcasters participating in the federal case include ABC, CBS Broadcasting Inc., NBCUniversal and Fox Television Studios. When contacted, an Aereo spokesperson declined to comment.

Related: Aereo to Broadcasters: Bring It On

Meanwhile, Aero continues to expand the regions where its service is available. This week it is starting service in Austin, Texas, ahead of the annual SXSW festival that takes place there. Last month, Aereo launched in San Antonio, Texas. 

In addition to its hometown of New York City, Aereo is also available in Boston, Atlanta, Miami, Salt Lake City, Houston, Dallas, Detroit, Denver, Baltimore and Cincinnati.

You can read the Justice Department's filing with the Supreme Court below.

13-461tsacUnitedStates.pdf


Related: Aereo Just Raised $34 Million to Expand 50 Percent in Next 3 Months