Copyright 10% rule

Often when I’m queried about whether copyright infringement has taken place, I’m asked about the 10% rule.  I’m not sure where this “rule” originated from but it’s a myth. It’s a myth to say that if you change a work by at least 10 or 20% that you’ve created a new work of copyright or that you’ve avoided infringing someone’s copyright.

Substantial Part

The rule which applies with regards to copyright (if you can call it a rule) is whether or not a “substantial part” has been copied or reproduced.

“Have they infringed my copyright?” or, “Have I infringed (their) copyright?” are not always straight-forward questions to answer.  It’s a question of judgement. There is no specific proportion or percentage that can be applied and it’s important to remember that the quality of the part used is more important than its quantity.

It’s possible to argue that if someone has used any part of your work that is recognisable and distinctive to the average person – and not just to you, regardless of how much has been copied, then they will have copied a “substantial part”. Each case will depend upon the particular circumstances and there is a large amount of case law on the subject.

If you’re using a part that is an important part of the whole work then chances are you’ll need to seek copyright permission.  Also, important is the purpose of the use – particularly if the use would compete with the copyright owner’s work.

If you can hold your hand on your heart and honestly say your came up with the works independently – and have proof – then it’s likely that you have not infringed someone else’s work – even though it may be the same or similar. For example, if you have drafts of what you’ve produced that could be compelling evidence in the court of law.

Just remember it’s not a percentage or quantity but a question of quality or whether a substantial part has been copied.