Dr Harris was a physicist who was writing a paper on K mesons.
He was a juror in the trial of Doctor Foreman. His initial vote was "guilty", and he resisted the arguments of several versions of the Doctor who had placed themselves on the jury. He was finally convinced to switch his vote to "not guilty" by the Second Doctor. After the trial, the Eighth Doctor apologised to him for their interference in the trial and then removed him from his time to the time vortex to protect the Web of Time. (PROSE: The Juror's Story)