He completed his secondary education in the top class at Raffles Institution in 1929, then worked as a clerk in a law firm before becoming a civil servant in the Official Assignee's office.

Encouraged by the Assistant Official Assignee, James Walter Davy Ambrose (who was later appointed a High Court Judge), to study law, Choor Singh enrolled as an external student at the University of London, passing the matriculation examination and intermediate LL.B.

In 1948 he was appointed a coroner, and the following year was elevated to the post of magistrate, becoming the first Indian to hold such a position in colonial Malaya.

Especially noted for his criminal judgments, Singh was the first Singapore judge to impose the death penalty on a woman.

One of the young Sikhs who founded the Singapore Khalsa Association in 1931, he served as its patron and honorary chairman of its board of trustees.

[6][7] Initially unemployed between 1930 and 1934 due to the Great Depression,[5] he subsequently worked for three years as a clerk in the law firm of Mallal & Namazie[1] for a monthly salary of 20 Straits dollars.

[8] Thereafter, he joined the Government Clerical Services for 60 Straits dollars a month and was posted to the Official Assignee's office, which was in charge of administering the estates of bankrupt persons.

The Assistant Official Assignee, James Walter Davy Ambrose (later a High Court Judge), advised Choor Singh to study law.

[7] This proved to be unnecessary; following a change in the rules, he was able to enrol as an external student at the University of London and passed the matriculation examination and, in 1948, the intermediate LL.B.

He was the first judge in Singapore to impose the death penalty on a woman, Mimi Wong, a cabaret singer who murdered her Japanese lover's wife in 1970.

Aside from this, Singh also heard the 1975 case of Sim Joo Keow, who was convicted of the manslaughter and dismemberment of her sister-in-law over a money matter, and sentenced her to ten years in jail.

[17] Impatient with nothing to do following his retirement, for about four and a half years from 1981 Choor Singh acted as a personal consultant for Tan Chin Tuan, the Chairman of the Oversea-Chinese Banking Corporation (OCBC), and other companies in the OCBC group such as Great Eastern Life and Overseas Assurance Corporation.

The High Court found that there was no actual bias, but there was evidence on which reasonable people might believe that Choor Singh might or could not bring an unprejudiced mind to the disciplinary inquiry.

The key finding was that the two private contacts with the material witness gave an appearance of a real likelihood of bias.

One of the young Sikhs who founded the Singapore Khalsa Association in 1931,[30] and having been its president in the 1960s,[31] he served as its patron and honorary chairman of the board of trustees.

Classes were conducted by the Sri Guru Nanak Satsang Sabha at two schools on Saturday mornings, and were attended by about 400 Sikh children.

The following self-written epitaph was published in his obituary notice in The Straits Times on 1 April 2009:[41] I came here by His grace After toiling in many lower lives.