Ms Lenz says this showed Universal wasn't taking fair use into account, and was acting in bad faith.

Over the following years, Ms Lenz - with the help of free-speech activists the Electronic Frontier Foundation (EFF) - won a series of court battles against Universal, most recently in 2015. That ruling found that "fair use is not just excused by the law, it is wholly authorised by the law".

But the Appeals Court also held that a "copyright owner cannot be liable simply because an unknowing mistake is made, even if the copyright owner acted unreasonably in making the mistake".

In other words, a rights holder can't be held liable for issuing a frivolous takedown notice if it can convince a jury it was a mistake, whether it was or not. Ms Lenz and the EFF have now filed a case with the Supreme Court to get that overturned.

"Left undisturbed, the ruling in this case gives a free pass to the censorship of online speech, particularly fair uses," the EFF's petition to the Supreme Court states.

"An author could cause a hosting service to take a critical review offline, without fear of consequence, if she held the mistaken view that the reviewer's use of a quote was unlawful. A political candidate who thought using an excerpt of her speech in a series of videos was necessarily infringing could flood her opponent's YouTube channel with takedown notices and cause it to be taken offline altogether in the middle of an election season, again without consequence."