Shouldn’t the lawyer have known already that the rule wasn’t in effect? Hell, I ain’t no lawyer but even I know that it’s kind of important to know the state of the law (or the rule in this case) on the date of the conduct.
It was all historical information. The documentary was filmed in 2002 but shown this year. Robinson was charged under the current rules. The lawyer concerned hasn’t said whether he actively dug up the information or came across it on the internet by chance.