I must admit to being puzzled, because when my g-g-f died in the asylum there was no court paperwork that I'm aware of, just a normal death certificate issued. He had a wife and 5 children (my grandfather was the youngest), who were living in western Queensland and he, too, died intestate. Can I ask why you think there would be court papers involved in your man's case?
The Queensland Archives have a rather large collection on Dunwich Benevolent Asylum and there are also bits and pieces about some of the inmates. I have a copy of g-g-f's admission papers (but not the reason for his being there) and the record of leave he took during his "stay". These came from the archive. I also have a copy of the page in the burials book (held by the cemetery) giving the date of burial and the number and location of his grave.
I had almost decided my research had given me all there was to learn about this period in my grand-father's life, but if you have uncovered a further avenue for investigation I'd be really pleased to hear about it.
Let's know what eventuates, won't you? Please?