The case brief always uses the specific version of the facts that the court uses in writing its opinion, whichever version that is. Therefore, in this case, your brief should state the facts as they were found by the trial court (i.e., you should use the defendant’s version of the facts).
Remember, your BRIEF is supposed to be a summary of HOW THIS APPELLATE COURT decided the legal issues in this case. Here, at least a majority of the members of the Washington Supreme Court that decided the Garratt v. Dailey case, accepted the TRIAL COURT’S finding of facts (acting in its role as fact-finder). The DEFENDANT’S version of these facts are contained in paragraph 3 of the edited version of this opinion. Therefore, THESE are the facts that should be included in your brief.