There are several key questions that need answering to understand this battle.
The music industry is arguing that those laws are outdated: they were designed for the web hosting providers and email services at the time, not the YouTube of 2016 with its billion viewers and huge music catalogue.
This leads in to the next thing that s fuelling the fire: some in the music industry think YouTube s massive catalogue of free music is making it harder for Spotify, Apple Music and other streaming services to persuade music fans to pay for their premium subscriptions.
Finally, YouTube is pointing to some of the musicians who have built careers on its service, such as violinist Lindsey Stirling, with her 8 million subscribers and estimated annual earnings of $6m from selling music and touring, as well as YouTube.
In the US and Europe, existing safe-harbour legislation is currently being reviewed, which is the main reason these arguments have blown up again in 2016.
Smarter heads within the music industry and beyond are starting to wonder whether the real problem is with online advertising itself: that if a big increase in YouTube streams only yields a tiny increase in royalties, perhaps that s a sign that as viewing rockets, even Google-backed YouTube is struggling to sell enough ads and keep the rates up.