Questione giuridica chiave
Whether the taxpayers could invoke the recusal of the tax court president only before the Federal Supreme Court and obtain annulment for lack of impartiality.
Decisione estratta
The recusal objection was raised too late; the right to rely on Article 30(1) BV was forfeited because the alleged ground could have been raised earlier once the court composition was knowable.
Motivazione estratta
A party must assert recusal grounds immediately upon learning, or being able to learn, the court's ordinary composition. The names of judges need not be expressly notified if they are accessible from public sources. Because the taxpayers could have discovered the president's role through the cantonal yearbook or the internet, they had to object in the cantonal proceedings.