WASHINGTON, DC Proponents of paying donors for bone marrow cells believe it could boost the number of people willing to participate in the current not-for-pay system.
The Obama administration is taking steps to block a federal court ruling that had opened a way to find out.
Buying or selling organs has long been illegal, and the 1984 ban also included bone marrow transplants.
The libertarian Institute for Justice sued the government to challenge the donor system, arguing that more people with rare marrow types might register to donate if they had a financial incentive.
Ultimately, a panel of the 9th U.S. Circuit Court of Appeals ruled that some, not all, marrow donors could be compensated -- citing a technological reason.
The government now has proposed a regulation to keep the ban intact.