courts are more likely to follow prior case law than attorney opinions
Except the memo is from the IRS Chief Counsel's office which represents the thinking of the IRS on the subject. It carries a LOT more weight than any random attorney's opinion.
The courts that have jurisdiction over federal income tax cases are federal courts and those are limited to the tax courts, the court of federal claims, and the federal district courts, federal appellate courts, and Supreme Court. The IRS is mostly free to disagree with and appeal decisions of all but the Supreme Court and appellate courts where certiorari has been denied. So it's a little dangerous to play fast and loose with decisions of lower courts and the reason for that is you're fighting city hall. If the IRS non-acquiesces in a tax court case and you get a notice of deficiency based on a position you took on your return you either need to pay or go to court. You can TRY to argue your position with the IRS but if they don't buy it and you decide to go to court it's going to cost you a few bucks and that could even be more than amount of tax you owe.
