In a Tax Court of Canada appeal, the Minister's assumptions of fact are presumed correct, and the taxpayer's task is to "demolish" them — to put forward credible evidence that displaces an assumption. The taxpayer makes out a prima facie case against an assumption, after which the evidentiary burden shifts to the Crown to prove the assumption on a balance of probabilities.
A prima facie case is one supported by evidence raising a degree of probability the assumption is wrong; it does not require certainty. Once an assumption is demolished and the Crown has nothing to put against it, the assumption falls and the reassessment built on it cannot stand. Much of trial preparation is identifying, assumption by assumption, what evidence will demolish each one.