While authorities rarely chase individual downloaders of old TV shows, your Internet Service Provider (ISP) monitors BitTorrent traffic. Many zip file sites actually lead to torrent magnet links. Uploading content (which happens automatically while you torrent) is a copyright violation. In countries like Germany or the US, you can receive settlement letters demanding thousands of dollars.
Most modern viewers do not need to download at all. Prison Break is available on: Prison Break Season 2 Download Zip File
If you want a permanent file, buy the season: While authorities rarely chase individual downloaders of old