This is just bizarre for so many reasons. Cohen was Trump’s attorney and their conversations and documents are almost always protected. The only time they are not protected is if the atty was involved in a criminal act with the client, or if the client tells the atty in advance that he is going to commit a crime. And even then only the issues related to the crime can be revealed, not unrelated atty-client work. But what is the crime in “knowing your son will meet with a Russian lawyer seeking dirt” and how is Cohen tied up in that crime? There may be a crime somewhere in there, I don’t know - but if there is Trump would be allowed to talk to his attorney about it and it would be privileged unless Cohen also participated in the crime.
The thing of it is, it is not really a legal question it is a political question. Mueller is not going to be able to charge Trump with a crime. So Mueller is trying to leverage anything he can for public consumption. If it isn’t going to go to a court of law, then there will be no judge to make evidentiary rulings, and no force of law that can sanction Mueller for breaking his ethical responsibilities. It is pretty low down dirty pool. And just like Mueller cannot charge Trump criminally, Mueller faces no consequences in the Trump related issues unless he tries to use the Cohen evidence to prosecute someone other than Trump. For all intents and purposes on the question of Trump Mueller is bound only by his personal ethics - the only way to stop him is to fire him.
One other point: Rob Goldstone - the British publicity agent who emailed Don Jr. about this “dirt on Hillary” - has publicly stated that there was no “Russian dirt” to trade. He says he was working for the people who wanted to repeal the Maginstksy Act, and that he made the “Russian dirt” story up in order to lure DJTJ into a meeting to discuss the Act.
DJTJ did say “I love it” and did go to the meeting. But I still don’t know what the crime is. If there was no information to buy sell or trade, then there can be no quid pro quo and no outside/Russian influence in the campaign.
One thing absurd about this is that while DJTJ stands accused of loving the idea of but never receiving any dirt from a foreign source, we know for a fact that British MI6 agent Steele was paid to gather and did provide information.