The topic of how to pay for new and experimental drugs will not go away. The government of the United Kingdom has announced a review of whether patients should be able to remain NHS patients if they pay privately for such drugs. The current controversy exposes broader challenges, including how widely patients should make additional copayments for NHS services, and how an “episode of care” should be consistently defined.

The NHS has changed radically since its foundation in 1948. Major breakthroughs in therapeutic drugs and applied technologies have offered new hope of prolonging life and improving quality of life in people with serious disease. Although drugs for cancer have hit the headlines, others that may have wider indications and applications are just around the corner. So should the NHS simply allow copayments to deal with the problem?

In reality, other health systems signal problems with this.Copayments mean that—contrary to the founding principles of the NHS—access to treatment depends …