I think this is covered by law in most countries regardless. In germany this would probably fall under §202a StGB the so called "Hacker paragraph". Its basically electronically trespassing. The law just requires that you are not allowed the access the information/data by me and I secured it/them in a reasonable way.
What if bitcoins are stolen without hack? For example "Random generator" bug(like was
https://bitcoin.org/en/alert/2013-08-11-android ) or if two people use same phrase for generate bitcoin address via "brainwallet".