How much can I rely on another work without permission?

There are no clear rules as to the amount of material you can use without permission. If in doubt, consult a legal advisor or look into copyright law for more information. In general, keep the rule of ‘fair use’ (see previous FAQ) in mind and consider how much and what part of the work you are borrowing. The more material you use, the less likely it is to be considered fair use. However, sometimes even a small amount of work proportionally can hold a lot of weight if it is an important part of the work, so the amount of text is not always the determining factor.