The esoteric tax and property-law issues at play in most will contests or contested probate proceedings are so complex that it’s become common practice in Florida to use experienced trusts and estates lawyers as expert witnesses in these trials.

But is it really proper to call a lawyer-expert to explain a body of law (no matter how complex) to the judge? Isn’t the judge supposed to “know” the law? And if there’s any explaining to do, isn’t that what counsel for the parties is supposed to do?

That was the question the trial judge was asked to rule upon recently in the trial of Anthony Marshall, the son of the philanthropist Brooke Astor. Here’s how the judge’s ruling was reported in Former Milbank Chairman to Testify as Wills Expert in Astor Trial:

Three months into the criminal trial of socialite Brooke Astor’s son, Anthony Marshall, and the lawyer he hired who allegedly helped him loot his mother’s estate, the presiding judge has cleared the way for a trusts and estate expert to testify for the prosecution.

Alexander D. Forger, the former chairman of Milbank, Tweed, Hadley & McCloy, can give expert testimony on the “patterns” of Astor’s wills and codicils and the “professional practice standards” for trusts and estates attorneys, Acting Supreme Court Justice A. Kirke Bartley Jr. ruled Wednesday from the bench.

However, the judge barred Forger from testifying on issues that could prove critical to the prosecution’s case: whether Henry Christensen III, who represented Astor for more than 20 years, and G. Warren Whitaker, the attorney who drafted a hotly disputed Jan. 12, 2004, codicil to the socialite’s 2002 will, violated ethical standards.

By the way, if you ever find yourself arguing either side of this issue, you’ll want to read the submissions of the prosecution and Marshall regarding Forger’s appearance. Both do a good job of articulating the classic arguments for and against allowing lawyers to testify as expert witnesses.

But is it OK under Florida law to qualify lawyers as “experts” to explain trusts and estates law issues to a judge? Like I said, it’s so commonly done, you’ll rarely if ever find yourself actually having to litigate the issue. But if you do find yourself having to argue this point, a case you’ll want to read – regardless of what side of the argument you may be on – is Guy v. Kight, 431 So.2d 653 (Fla. 5th DCA 1983), which provides as follows:

Section 90.703, Florida Statutes (1981) provides that “[t]estimony in the form of an opinion or inference otherwise admissible is not objectionable because it includes an ultimate issue to be decided by the trier of fact.” Additionally, it has been held that there is no error in permitting an attorney to testify as an expert witness at trial as to substantive and procedural Florida law. Warwick, Paul & Warwick v. Dotter, 190 So.2d 596 (Fla. 4th DCA 1966).

Another source you should review if you’re thinking about serving as an expert witness yourself or engaging another attorney as an expert witness is ABA Formal Ethics Opinon 97-407 (Lawyer as Expert Witness or Expert Consultant).