MAME is legal. Downloading ROMs for games you do not own the original arcade PCB (printed circuit board) for is a legal gray area in most countries. We do not condone piracy. This guide is for educational and archival purposes for software you legally own.
The legality of downloading and using MAME ROMs is a complex issue. While the MAME emulator itself is legal, the use of ROMs without permission from the copyright holders may be considered copyright infringement. Users should be aware of the laws in their country and consider purchasing the original games or obtaining permission from the copyright holders to use the ROMs. Mame Roms UPD Full Pack Download
Here are some points to consider: