@OVienna
*MM's letter to her father - contents already in the public domain thanks to MM's leakage of letter to friends and willing dissemination to People magazine. Mr Markle felt he had the right to state his own case contrary to this account and relied on a letter addressed to him to do so. We'll soon see what the judge's take is on it all.
PC's letters to ministers - tried his darnest to keep these quiet but the judge disagreed.*
You do not 'leak' info to your friends, you discuss it. Leaking to your friends, that is not a thing. Copyright laws are quite straightforward, I am surprised this case is taking so long tbh.
For an example, Harry Styles writes a song for his ex and sends it to her. He talks about the song to friends, they tell everyone, including talking about it at a radio station. She claims, they are not quite correct about the details, and plays the song to a radio station. The radio station, then has to ask for permission from HS to play the song, the only thing they can do is talk about it, but not play it.
Not too sure what you mean about PC, but he won his case.