CIVIL LIBERTIES GROUPS and Attorney General John D. Ashcroft don't often agree. Yet both quickly sounded the alarm at the news that the Bush administration has begun considering the creation of a domestic intelligence agency. Civil libertarians warn that any such agency could be beyond control; Mr. Ashcroft denounced the idea as antithetical to his own efforts to make law enforcement and intelligence work closely together. "The establishment of a separate, distinct agency would be to move in the other direction," he said recently. "Instead of to integrate and cooperate and communicate, it would be to segregate." His objections, and the civil libertarians', are substantive. But the idea should not be so quickly dismissed. While FBI Director Robert S. Mueller III is trying to remake the FBI into an effective counterterrorism force, he may not succeed. Alternatives should be explored.

Two issues need to be separated: the rules governing domestic spying and the agency charged with doing the job. No agency should collect domestic intelligence -- that is, spy -- on Americans who are not working on behalf of a foreign power. If such people are committing crimes, that is the business of law enforcement. If not, government has no business in their business. That principle should be the same for the FBI as for some hypothetical agency. The key questions are whether a new agency would likely be more effective than the bureau and whether it would be more or less prone to abuse.

The bureau is no stranger to domestic intelligence operations -- catching spies and watching potential terrorists. The notion that there is something radically new about an agency collecting foreign intelligence domestically is wrong. But the FBI does have a history of abusing its powers while collecting intelligence; and foreign intelligence, while part of its mission, is not its soul. Agents join the bureau to catch crooks, which is the guts of their training. Crime-fighting also offers the best means of professional advancement. Intelligence analysis is not the FBI's strong suit. Neither is dissemination of intelligence that the bureau obtains. True, there have been significant counterterrorism successes despite these impediments. But the FBI's institutional culture clearly led to missed opportunities in the months and years before Sept. 11, 2001. Mr. Ashcroft may be right that a devoted intelligence agency could never bridge intelligence and law enforcement as well as the FBI. But we think it is reasonable to ask whether an organization dedicated to collecting and analyzing foreign intelligence in order to protect domestic security might have more success.

Would such an agency be more likely to infringe on civil liberties? It might be argued that the relationship between the FBI and the Justice Department engenders a degree of discipline about the rule of law -- an awareness on the part of FBI agents that the information they collect and the means they use to collect it must ultimately pass muster in court. An organization steeped in the secrecy of the intelligence world might balk at respecting such constraints.

On the other hand, an agency focused narrowly on intelligence and counterterrorism might not be likely to cut as wide a swath through the population as the currently configured FBI. At any rate, entrenched turf concerns should not stand in the way of a sober investigation of the potential costs and benefits of creating a new agency. Clearly, the current system has not performed so well as to preempt further discussion.