The ABA sent a cease-and-desist letter to Greg Thatcher, whose web site listed and indexed the routing numbers, and demanded that he take down the numbers. (After a 1991 Supreme Court decision, most competent copyright lawyers would never even have made such a claim, but never mind.)
Mr. Thatcher obtained pro bono counsel to represent him. That lawyer, Andrew Delaney, wrote one of the best responses to a cease-and-desist letter ever. On the merits, the letter points out that (1) things like routing numbers aren't subject to copyright protection, (2) since the numbers were published without a copyright notice starting in 1911, any copyright would be lost for numbers published during the time the 1909 Copyright Act applied, and (3) Thatcher's use of the numbers would be fair use anyway.
But the best part is the humor in the letter. Especially the footnotes. Such as footnote 7: "And we went to law school, which just illustrates how gullible we are." And then there's the closing offer to accept service of process on behalf of Thatcher:
If you do feel it's necessary to sue our client, we are open Monday through Friday from 8:00 A.M. to 6:00 P.M. and we have lollipops for people who serve process. So if you do file a complaint and send someone over with a summons, please have them wear something with a bit of purple . . . we all like purple.