UNLESS HOUSE SPEAKER Thomas P. O'Neill says no, the new official system for broadcasting House floor proceedings is going to give congressional incumbents yet another way to promote themselves back home -- at the taxpayers' expense. Since last summer, the House had made the sound of floor debates available to broadcasters and the public. Nothing bars any representative from making or ordering a tape of his own remarks or any other snippets of debate, editing that tape as he chooses, and transmitting it as a news report to broadcast outlets back home. Apparently few members have caught on to the full publicity potential here. But once video coverage also becomes available, a month or so from now, it won't be long before every incumbent with any hustle is keeping his district's stations amply supplied with self-promoting tapes -- labeled as "official House proceedings" and paid for by the taxpayers.

It's not as though members of Congress don't already have ample facilities for making radio and television tapes to ship back home at public expense. But those materials are more clearly self-produced and thus as suspect as any other press release. Cuts from the floor debates will have an institutional ring of objectivity and authenticity that may increase their chances of being used on the evening news. And that compounds the problem, because there will be no assurance that the tapes are really accurate at all. An incumbent could easily edit a tape of a floor speech to eliminate verbal gaffes, much as the Congressional Record is tidied up every day. Beyond that, tapes could be cut and spliced to distort the debate or put opposing viewpoints in an unflattering light.

The House resolution governing the broadcasting system does not prohibit any of that. It does bar "political" and "commercial" uses of the electronic record, but nobody has spelled out what those terms mean. By offering tapes as "official news," incumbents might even be able to get ground equal-time rules -- which don't apply to news events -- and dominate the home-town airwaves druing campaigns.

All this puts a great burden on the broadcasters involved. In principle, they have a professional obligation to check the accuracy of material they receive, to reject doctored reports, and to tell viewers the sources of the sounds and images they air. In practice, many stations -- especially smaller ones -- may lack the time and resources to do this whenever the congressman's office transmits a hot report. Of course, broadcasters who take too many liberties with the news are accountable at license-renewal time, just as incumbents are answerable at the polls. But those sanctions come, if at all, after the fact. To ward off a whole host of problems, the House should agree right now that members should not use the official sounds and pictures to publicize themselves.