Robin's perspective is that of a design writer and publisher interested in reproducing fine historical examples of significant design. Mine is a little different – I typically want to show everyday documents as examples of a category, or to critique them (often negatively, for example drawing attention to outrageously small type in a consumer contract).
Copyright law is designed to protect writers, artists, designers and publishers from being ripped off, but there is provision for fair dealing for the purpose of criticism and review.
The problem is that publishers insist on playing it safe and getting permission. This gives you two problems. Most often it is 'who do you call?' if you want to reproduce part of, say, a credit card application form, or a car rental agreement. And secondly, these companies just aren't set up to respond, and even if you can get through they probably don't want you to reproduce it if you are going to knock it.
Robin quotes a famous judgement of Lord Denning about fair use – it's all a matter of context, intention and degree.
So here's my take on how the spirit of fair dealing might apply to reproducing information design:
Clearly fair dealing
– Showing something you are selling (eg, second-hand book dealer showing a thumbnail of a book cover).
– Showing something because it happens to be in a photo with another purpose (a book lying on a table, a poster on the wall).
The grey area (uses which I think are fair but journal/book publishers may not)
– Showing something as an exemplar of a category (eg, typical covers from romantic novels to illustrate a genre - you could pick any one from thousands).
– Showing an object or design that is ubiquitous (Mars Bar wrapper).
– Showing an object that is freely viewable in public (street sign, shop front).
– Showing something to critique its design or wording, including negative comments.
– Showing something as an exemplar, where you don't know the owner's identity or cannot trace them, or they have not replied.
– Redesigning something as a demonstration of design principles, although using some or all of the original text.
Not fair dealing
– Showing something when you have asked permission but it has been refused (even though it appears to be a fair use).
– Showing something (as an art object) that museums have invested in (as an art object), and need to potentially earn income from.
– Reproducing so much of something that people don't need to buy their own copy.
– Showing something as an example of a designers work, but at full size and in a form that could be used as a design object (eg, as a poster).
– Using the work for its original purpose to save effort (eg, copying the design and wording of a form).
– Using the work in imitation of the original (passing off). Supermarket own label brands cross this line all the time, of course.