Ah, OK. I’m not familiar with specific suit, although aware of the general issue between the government and encryption community and the government over export restrictions. I had read quite a bit about it at one point. I might have read about this case, and if I looked into it, it would jog my memory.
At the time cryptography export restrictions as a munition prevented the disk from being exported. However the book could be exported since it was only text. Thus the government's reason for banning the disk assumes nobody in any foreign country knows how to type.
Karn sued over export of the disk. It was a thorn in the administration's side, and I believe led them to realize the export restrictions were stupid. Remember, this was also a time when US businesses had to ship lower-encryption products overseas, killing their ability to be competitive with foreign companies who could use the full encryption in their products. Karn thus incidentally did a lot for the US software business.
A related issue was Phil Zimmermann's Pretty Good Privacy. The Clinton administration hounded him for years because people had exported PGP. To show the idiocy, Phil published a book with the source, and foreigners scanned it in, compiled it and put it on the Internet. Thus you could download a legal version of PGP from a foreign source (IIRC, Finland was popular), but not from Phil here in the US since he couldn't publish it in a place where it could be easily downloaded to a foreign country without Clinton's goons nailing him.