The US President's Council of Advisors on Science and Technology (PCAST) has rarely fulfilled the full potential of its nominal role, which is to provide the most powerful elected official in the world with scientific advice.

In theory, the presidentially appointed panel could keep the president informed on key science- and technology-related issues, ranging from avian flu and global warming to computer viruses and nuclear-weapons proliferation.

The president's discretion in appointing the panel himself is not conducive to the delivery of solid or unwelcome advice.

In practice, however, the panel has never lived up to that ideal. It came closest, perhaps, under the first President Bush, who graced PCAST meetings with his presence. The panel was active but not particularly influential under Bill Clinton, and has been almost invisible under the current president.

So the news that PCAST is to be merged with another, even more obscure panel, the President's Information Technology Advisory Committee (PITAC), will make few waves. Nonetheless, the amalgamation of the panels, and the expansion of the possible number of members from 25 to an unwieldy 45, portends a possible weakening of the voice of science in the White House.

PCAST has already confined itself to the relative arcana of science policy. At the moment, for example, it is evaluating the effectiveness of the National Nanotechnology Initiative — a worthwhile exercise, but hardly one that is likely to grab the president's attention.

Floyd Kvamme, a venture capitalist who co-chairs PCAST with John Marburger, the president's science adviser, says the new panel will operate much as before, with the new work delegated to appropriate subcommittees. But unless the panel becomes considerably more active, its new role overseeing all the information-technology research initiatives in the federal government may mean that less time and resources are available to work on science issues. This marks a continuation of the tendency of the Bush administration to marginalize the voices of science in its internal deliberations.

One of the difficulties that will always face a body such as PCAST is the sheer vastness of the territory it is supposed to cover. These days, advice on specific scientific questions will often require detailed specializations that few PCAST members will possess. At the same time, there is a tendency for officially designated advisory bodies that are required by US law to meet in public — such as PCAST — to shun robust discussion of substantive issues. Finally, the president's discretion in appointing the entire panel himself is not conducive to the delivery of solid and occasionally unwelcome advice.

PCAST is the latest in a series of similar panels stretching back to the administration of Harry Truman. Some have been more active and influential than others, depending largely on the president's own interest in science and his relationship with the chief science adviser. Perhaps a future administration will develop the committee's role and profile instead of neglecting it — but even then, the panel's preeminence will last only as long at that president's term in office.