What is the primary legal consideration when repurposing online content under 'fair use'?

The primary legal consideration when repurposing online content under 'fair use' is determining whether the new use is 'transformative'. 'Fair use' is a legal doctrine that allows the use of copyrighted material without permission from the copyright holder under certain circumstances. A transformative use adds new expression, meaning, or message to the original copyrighted work. A use is more likely to be considered fair if it transforms the original work, rather than merely reproducing it. Courts evaluate transformative use by considering factors like the purpose and character of the use (commercial vs. non-profit, educational), the nature of the copyrighted work (factual or creative), the amount and substantiality of the portion used in relation to the copyrighted work as a whole, and the effect of the use upon the potential market for or value of the copyrighted work. For example, using a short clip from a movie in a film review is more likely to be considered fair use if the review provides commentary and criticism that transforms the clip into a new, analytical work. In contrast, simply re-uploading the entire movie to a different platform would not be considered fair use because it does not transform the original work and directly competes with the copyright holder's market.