> consider the case of translating a literary work between languages: this is a classic example of a derivative work This is a classic example of "you need a l

> consider the case of translating a literary work between languages: this is a classic example of a derivative work This is a classic example of "you need a license on the original material to sell it" (unless it is public domain) You need the rights also if you are translating from a pre existing translation in a different language (i.e. you're translating a Japanese book from the French authorized translation). Translating an opera is not automatically derivative work and does not fall under the umbrella of fair use. source: my sister is a professional translator EDIT: technically you'd need to acquire the rights even if you translate it by yourself, for fun, and show it to someone else.