Wikipedia has a pretty interesting discussion of the ever changing boundaries of Fair Use with respect to copyright under American law. The case that seems closest to the situation The Armed Citizen is confronting is Los Angeles Times v. Free Republic LLC (C.D.Cal. 2000) -- and even here, there are substantial differences that would seem to benefit us, especially that the Los Angeles Times was actually selling the articles that Free Republic was posting in full. That is not the case with the articles in dispute from the Review-Journal. That Free Republic was essentially a commercial operation, not a scholarly function. I think there is at least a plausible claim that where there is uncertainty, it is most logical to err on the side of leniency.
If I am to believe the claims in the Wikipedia article, Justice Story's decision sitting as a circuit judge in Folsom v. Marsh (1841) determined that a major factor in determining whether someone was injured by copying is:
The entirety of the copyright is the property of the author; and it is no defence, that another person has appropriated a part, and not the whole, of any property. Neither does it necessarily depend upon the quantity taken, whether it is an infringement of the copyright or not. It is often affected by other considerations, the value of the materials taken, and the importance of it to the sale of the original work.Indeed, that seems to be what sank Free Republic--their actions clearly impaired the marketability of the articles that the Los Angeles Times was selling. There might be a good case that loss of advertising revenue connected to the Times website was substantial--but that's not likely even close to 1% of the $75,000 RightHaven is demanding.