In response to a reader’s question about the use of “which” in a 1934 US Supreme Court opinion, the author explains that “which” is used as a relative adjective to avoid ambiguity. While this usage is not as common nowadays, it still appears occasionally. The Oxford English Dictionary defines “which” in this context as a relative adjective that introduces a clause while modifying a noun. The usage dates back to Anglo-Saxon times and has evolved over centuries. The reason for its decrease in usage is unclear, but there are other ways to clarify sentences in modern English. Overall, the author provides historical context and alternative phrasing options for the reader’s query.
https://www.grammarphobia.com/blog/2023/09/which-3.html