They've called "white space" applications threats to public safety and even likened them to germs. Now they're calling them illegal. The National Association of Broadcasters and Association for Maximum Service Television (MSTV) have sued the Federal Communications Commission over its decision to authorize unlicensed devices for sending and receiving broadband over unused television channels. NAB represents hundreds of TV license owners. MSTV speaks for the industry on spectrum/policy issues.

"As several engineering tests have shown, portable, unlicensed personal device operation in the same band as TV broadcasting continues to be a guaranteed recipe for producing interference," NAB Media Relations director Kris Jones told Ars Tuesday morning. "NAB will continue to advocate on behalf of the millions of American households who rely on broadcast television for entertainment, news and information."

The suit was filed in the United States Court of Appeals for the District of Columbia Circuit on February 27, but neither NAB nor MSTV appear to have been in a big rush to publicize the move. The petition for review charges that the FCC's decision "will have a direct adverse impact on MSTV's and NAB's members because it will allow harmful interference with reception of their broadcast signals."

It's unclear from the document on exactly what legal grounds NAB/MSTV think the FCC's decision is actionable. The petition calls the Commission's Second Report and Order, which gave the go-ahead to the manufacture and distribution of white space apps, "arbitrary, capricious, and otherwise not in accordance with law." That suggests that the complainers might invoke the Administrative Procedures Act in this case. In any event, they obviously want the courts to throw the decision out.

This suit does not seem to have shocked the pro-white space crowd. Jake Ward, spokesperson for the Wireless Innovation Alliance, called the action "disappointing, but certainly not surprising." WIA represents various manufacturers, software companies, and public interest groups.

"For decades, [the broadcasters'] policy has been to stifle innovation at all costs and ask questions later and this is no different," Ward added. "White Space technology works, it is safe, and the Federal Communications Commission knows better than anyone the steps that must be taken to ensure that continues to be the case. A legal challenge to the process and the Commission's expertise in this area is just another in a long list of ill advised and futile delay tactics."

This legal action comes as the FCC was just starting to implement its white space order. The agency finally published the decision in the Federal Register in mid-February, announcing that its rules would become effective on March 19. And the Commission has begun talking to parties about setting up the databases needed to protect TV channels and unlicensed microphones from interference.

On February 27, a small boatload of public interest groups met with the agency to discuss, among other matters, "the possibility of the Commission issuing a Notice of Inquiry on allowing higher power levels for White Spaces devices in rural areas."

No predictions from here on where all this is going now that a lawsuit has entered the picture. According to the NAB/MSTV case docket, the trade groups have until April 1 to file their Statement of Issues with the court. Ars contacted the FCC for a comment on the suit, but has yet to receive a reply.