Why couldn't the court operate in Kowloon's Walled City?

This was due to an anomaly in the treaty made between the UK and China when the UK leased the New Territories from China (previously it only had the island). It was originally a Chinese fort.

"The fort’s fate changed in 1898 when the New Territories were leased to Britain for 99 years. Although the walled city remained Chinese territory by treaty, the following year their troops and officials were forced to vacate. Behind them they left a power vacuum that was filled by criminals, and the garrison became a city within a city.

Throughout the 20th century, fugitives and other criminal elements flocked to the lawless enclave. Beyond the reach of the law, the area mushroomed into a squalid maze of illegally constructed buildings, where everything from drug trafficking and prostitution to unlicensed dentistry flourished in a labyrinth of dank, dark alleyways."

Police raids were very, very rare.

I went into the area in 1980 with my husband, a Hong Kong Chinese friend and his US girl friend. The Chinese guy said he wouldn't go in alone, but that 'they' wouldn't do anything to him when he was with 'gwei lo'. This slang word used to mean 'foreign devil', but is now said to mean 'ghost man', referring to white skinned people.

We didn't see much, because he was a dentist and was fascinated by the primitive dentist equipment. The dentists worked in full view of passers-by. We couldn't drag him away!

In 1987 the British authorities took control of the area and, with the agreement of the Chinese government, the area was cleared and the residents resettled. It is now a park.