The Petitioner, who was one of 15 candidates in an English Parliamentary By-Election, alleged that his vote count of 50 was fraudulently pre-determined. The expert statistician for the Petitioner based his opinion solely on the evidence of the Petitioner, which was contested. He was unaware of the contents of the Respondents’ witness statements and had not taken them into account.

This is an important judgment for experts instructed in cases where there is an issue as to whether thrombolysis should have been carried out following a stroke. The court considered a number of relevant publications.

For experts in psychiatry and psychology, it is important as it illustrates how the court tests evidence in cases involving performance validity testing.

Hakmi v East & North Hertfordshire NHS Trust [2025] EWHC 2597 (KB)