If my friend has a CD can I make a copy of it on my device?
It is controversial. Some poskim say that for private use it is permitted, while others say that it is genieva. L’ chatchila I wouldn’t do it. But aside from the halacha, it isn’t an ethical thing to do, the producers work very hard to make the tapes and they really mind when people copy their cd and don’t buy them.
Igros Moshe O:CH 4-40 (9), R’ Eliyashiv, and R’ Y. Belski held that it is assur. On the other hand R’ S. Z. Auerbach, and R’ Vosner zt”l held that it is permitted.