In ordering Kathleen Sebelius to ignore federal policy and allow 10-year-old Sarah Murnaghan and 11-year-old Javier Acosta to join the adult waiting list for lung transplants this week, U.S. District Court Judge Michael Baylson declared that the policy "discriminates against children and serves no purpose, is arbitrary, capricious and an abuse of discretion."

What in the world made him say that?

The order means that Sarah and Javier will be added to the adult waiting list for donor lungs, while they also remain on the children's list. This may -- or may not -- shorten the children's wait time and save their lives.

The judge is wrong about the policy, however, and wrong to say Sebelius should have simply waived it.

In a country where nearly 1,700 people are waiting for a donor lung, including 30 children, a sound and carefully monitored policy is needed to see that scarce organs are given to patients who need and can benefit from them most. That is exactly what we already have.

The system used by the Organ Procurement and Transplantation Network -- a public-private operation managed by doctors, surgeons and others with experience and expertise in organ transplantation -- is based on the historical data showing how transplant patients fare medically. Patients on the waiting list have a "lung allocation score" indicating their need for a transplant and how well they can be expected to do if they get one. Those with a score of 75 or more are considered high-priority; those with a score under 50 are low-priority.

Children under 12 have a separate list in part because, given how few young kids have received transplants, the data on them is very sparse and unreliable, so they can't be categorized by need objectively. They develop priority by spending time on their list.

What's more, at the time that the scoring system was being devised, many lungs from child donors were being transplanted into adolescents and adults, and it was felt that these organs should instead be specially reserved for young patients in need.

So far there has been no evidence that the system has made things worse for small children. On the contrary, the under-12 group has traditionally fared better in terms of "waiting list mortality" (the ratio of deaths on the waiting list to time spent waiting) than the adult group has. This measure has increased for young children in recent years but remains lower than that for adolescents and adults.

These and much other data are continually evaluated and the system is reviewed every year. The age rule is not the only thing that comes up for revision. New research suggests, for instance, that it may be wise to allow high-priority patients to receive donor organs from a wider geographic area than is now allowed.

Now, in response to Judge Baylson's order on Sarah Murnaghan, leaders of the OPTN's thoracic committee have begun a special review of the two-tier allocation process. The committee will also hear from other experts and from the public and then determine whether eliminating the age divide, or making any other change in the way patients are prioritized, is warranted.

The committee presumably could also consider creating a mechanism for allowing children onto the adult waiting list in highly exceptional circumstances. (The cases of Sarah and Javier are extraordinarily dire. Sarah is reported to have an adult LAS score of 78, which would place her high on the older patients' waiting list. Most children under 12 who are waiting for transplants would not have scores high enough to give them great priority on the adult list.)

Ideally, no child and no adult would ever run out of time waiting for a transplant. For this, more Americans must become organ donors. Various strategies have been proposed to increase the number -- from offering to pay funeral expenses for donors to having all citizens be considered donors unless they express a desire not to be (an opt-out system, rather than the opt-in one we have now). Policy makers should turn their attention to proposals such as these and be glad the transplant waiting-list system is already well taken care of.

(Mary Duenwald is a member of the Bloomberg View editorial board.)