WHAT COULD GO WRONG? A Federal Ban on Making Lethal Viruses Is Lifted.

Such work can now proceed, said Dr. Francis S. Collins, the head of the National Institutes of Health, but only if a scientific panel decides that the benefits justify the risks.

Some scientists are eager to pursue these studies because they may show, for example, how a bird flu could mutate to more easily infect humans, or could yield clues to making a better vaccine.

Critics say these researchers risk creating a monster germ that could escape the lab and seed a pandemic.

Now, a government panel will require that researchers show that their studies in this area are scientifically sound and that they will be done in a high-security lab.

The pathogen to be modified must pose a serious health threat, and the work must produce knowledge — such as a vaccine — that would benefit humans. Finally, there must be no safer way to do the research.

“We see this as a rigorous policy,” Dr. Collins said. “We want to be sure we’re doing this right.”

The Army of the Twelve Monkeys smiles.