I was thinking of writing a magazine article on a rabbi I knew well before his death some years back. I wrote to his son to see if he could help me with stories, history, photographs, etc. He declined, worried that he might speak loshon hara about the members of the community, and he wanted me to make sure that I was familiar with the "halachos" regarding writing a biography of a gadol. To be frank, I had no idea that there were specific halachos on this subject. Could someone explain to me what he is talking about? Is it something beyond shimiras haloshon?
There is no official set of laws called "hilchos biography", perhaps he was using the word "Hilchos" colloquially to say "do you know the way to go about writing a biography" ie. How to phrase certain things, what to leave out, what names to change etc.
However, there are Laws of Slander and Gossip, as well as embarrassment. And those halachos should guide the author in his attempt to draw a sketch of the person being written about.
In the desire to show the greatness of the personality being written about, too often the prohibition of Lashon Harah is glossed over.
Furthermore, a biographer must know the audience he is writing to, some things which in different cultural milieus would have been understood and taken for granted, might be grossly misunderstood in our day and age, and therefore embarrassing to the family of the deceased.
Thus, I would assume the son meant the concerns mentioned above when he said you must know the "halachos" of writing a biography.