Well, back in 1995, that is 🙂 See his post Bye-Bye for IP, an excellent short critique of “intellectual property.” As I noted in the comments, I think I tied him in coming to my senses about IP: I believe my first published piece against IP was in 1995 as well in the IOS Journal. There may have been something earlier; I’m not sure. I may have presented something a bit earlier at some Federalist Society meetings in Philadelphia; the next thing I can find that I published was in 1998 for the Pennsylvania Bar Association Intellectual Property Newsletter (later republished in a Federalist Society online forum).
The 1995 publication followed on the heels of my taking the patent bar exam in 1994. I had been thinking about IP for a long time, since 1987 or so at least, because Rand’s defense of IP had always bugged me. I started thinking about it harder in 1992 or so, when I started practicing IP law.