The second week in October is when the world’s leading scientists eagerly await a telephone call from Stockholm with life-changing news they have been awarded a Nobel Prize. According to the Nobel Foundation, “In no case may a prize amount be divided between more than three persons.” Known colloquially as “The Rule of Three,” this statute has, over the years, led to considerable controversy. This year was no different.

The Nobel Prize in Chemistry for 2020 was awarded jointly to Emmanuelle Charpentier and Jennifer Doudna (seen above right) for “the development of a method for genome editing.” They pioneered CRISPR, an acronym for “clustered regularly interspaced short palindromic repeats,” that enables scientists to cut, copy and replace sections of DNA. This was the first time two women had been jointly honoured, but was a third person overlooked for the award? It turns out two men were considered unfortunate – Virginijus Šikšnys of Lithuania whose paper was held up during review, and Feng Zhang of the USA who showed that CRISPR worked in mammalian cells.

The Nobel Prize in Medicine for 2020 was awarded jointly to Harvey Alter, Michael Houghton and Charles Rice for “the discovery of Hepatitis C virus.” The committee was unable to contact Houghton before announcing the award and there were concerns he might turn it down as he had previously refused a major award because two co-workers were excluded. Houghton accepted the Nobel but said future committees should seriously reconsider “The Rule of Three.”

The Nobel Prize in Physics for 2020 was divided, one half awarded to Roger Penrose for “the discovery that black hole formation is a robust prediction of the general theory of relativity,” and the other half jointly to Reinhard Genzel and Andrea Ghez for “the discovery of a supermassive compact object at the centre of our galaxy.” Had Penrose’s longtime collaborator Stephen Hawking still been alive, the committee would have faced a tough decision.

Three Nobel Prizes have been awarded in medical imaging – for X-rays, computer tomography (CT) and magnetic resonance imaging (MRI) – and each was controversial. Wilhelm Röntgen received his award in 1901 for the discovery of X-rays but the seminal contributions of Ivan Puluj were overlooked. In 1979, neurologist William Oldendorf believed he should have shared the award for the CT scanner with Allan Cormack and Godfrey Hounsfield (seen above with Torgny Greitz), while in 2003, Raymond Damadian was bitterly disappointed when the award for MRI was given to Paul Lauterbur and Peter Mansfield. “The Rule of Three” statute could have assisted Puluj, Oldendorf and Damadian, but the committee’s decisions are always final.