Fair use is a US legal doctrine that permits limited use of copyrighted material without acquiring permission from the rights holders. The Society for Cinema and Media Studies (SCMS) has published a statement on fair-use policies here. Also, the SCMS published a best practices document for film and media studies writings. Keep in mind that fair-use isn’t applicable for all countries. In the Netherlands for instance, there is no such thing as fair-use. Permission from rights holders is always needed. Please note that fair-use isn’t the same thing as academic citation right.