Professor Humbach teaches courses in the law of property, legal ethics, criminal law and the First Amendment. His teaching specialty has been in the property law area for over 40 years.

Prior to entering law teaching in 1971, Professor Humbach practiced corporate and securities law in New York City. Most of his teaching experience before coming to Pace in 1977 was at Fordham Law School, but he also taught at Brooklyn Law School and as a visiting professor at the University of Illinois and the University of Hawaii. He has authored a number of articles in various property law areas such as landlord-tenant and the Takings Clause as well as, more recently, on the implications of modern neuroscience for the criminal law and justice. Other published scholarhsip includes articles on the First Amendment, legal ethics and the legal profession. He has also produced computer-assisted instruction tutorials on the Estate System and Future Interests for first-year property students, which are freely available online. (See below).

Long engaged in land conservation activities, he was a leader in the successful effort to achieve permanent protection for Sterling Forest, a 22,000 acres natural preserve at the edge of the NYC metropolitan area. He has also served on the boards of directors of the Appalachian Mountain Club and the NY-NJ Trail Conference and as chairman of his community Architectural Review Board.