That wasn't Brackett's fault, Chandler famously said he didn't know who killed the chauffeur. Like many of his novels The Big Sleep was made by combining two or more of his short stories, and sometimes things didn't make sense.

Nice detail. I really enjoy the movie scene for scene and it had to be pointed out to me that it makes no sense.

I suppose that is the magic of movies. The suspension of disbelief.

An excellent detective novel as well. Loved it in high school.