Are drones useful tools in the arsenal of law enforcement, high-tech toys or a serious threat to Americans' freedom and privacy? All of the above. The Virginia General Assembly's plan for a two-year ban on the use of drones by law enforcement comes at a moment when the technology is developing faster than society's ability to comprehend the consequences.

Virginia has been accused of hypocrisy for wanting to impose a timeout while also seeking to become the site of one of six congressionally mandated drone test sites. The criticism, however, is ill-founded. There is no contradiction between continuing research on drones while at the same time giving state lawmakers time to craft sensible long-term policies governing their use.

Drones are here, and law enforcement will use them. This fact cannot be undone. But state lawmakers can act now to head off abuses before they occur, protecting citizens against intrusive uses of the new technology. The American Civil Liberties Union has recommended limits on the use of domestic drones, including requiring warrants before they are used in criminal cases and a strict ban on their weaponization.

We'd like to see states go even further. One Virginia municipality -- Charlottesville -- was among the first in America to ban drones outright. That may be going too far, but the city's resolution also called on state and federal governments to prohibit the use of evidence collected by drones from being used in criminal cases. And this is a lead that the commonwealth and other states should follow.

Drones will someday serve as a cheaper and safer substitute for helicopters. They can assist in manhunts, in hot pursuit of fleeing criminals, in monitoring hostage situations, rescues and accident investigations.

But how to separate these useful functions from the potential for civil liberties abuses? Here is the general guideline we urge states to adopt pre-emptively: Police should be required to publish, online and in real time (or with an hour's delay at most), maps tracking where all of their drones are at every moment, with a clear explanation of what they are doing. Especially if there is a slight delay, this will not interfere with the legitimate uses outlined above, and it will prevent most abuses. As an extra safeguard, drones should be specifically banned from assisting in certain police activities that are legitimately conducted by other means, such as investigatory criminal surveillance and speed traps.

The first American arrested with the help of a warrantless drone was Rodney Brossart, a farmer from Lakota, N.D. A predator drone helped a SWAT team arrest Brossart for failing to return six cows belonging to his neighbor until the neighbor paid for the feed they had consumed. The story illustrates how the availability of technology can give idle policemen an opportunity to meddle. In this case, a minor matter for the civil courts instead became an over-the-top case of Big Brother surveillance and abuse of police power.

The Electronic Privacy Information Center reports that federal specifications for drones include the ability to identify "a standing human being at night as likely armed or not" and the ability to intercept cellphone conversations. This raises real concerns about potential violations of First and Second amendment rights, prompting civil libertarians' new catchphrase: NOMBY, or "Not Over My Back Yard."