You may need a copyright clearance if your film is based on someone else's account of those incidents (for example, in a book). You are likely to need a copyright clearance if:

• that account is protected by copyright, and

• the copyright has not expired, and

• your film uses a "substantial part" of that account.

Legal obligations other than copyright might also apply. These could include legal obligations relating to misrepresentation of facts (such as defamation), and legal obligations relating to confidential information.