Prof. Marshall of Yale -- Truth or Urban Legend?

There are rumors circulating in print and on the Internet that J. Howard Marshall, the deceased husband of Anna Nicole Smith whose case is currently before the United States Supreme Court, was at one time a law professor at Yale who specialized in wills and trusts. 

I've been able to confirm to my satisfaction that Mr. Marshall graduated from Yale Law School in 1931 and served as an assistant dean.  However, I am uncertain about the validity of the "law professor" and "wills and trusts specialist" part of the claim.

Let me know if you have any good leads!