The presiding judge said the action of the 23-year-old defendant and a group of other Breakfree activists was justified by the climate emergency and was in line with the logic of the Swiss government climate policy.
However, the court warned the verdict must not be seen as an encouragement to commit further damage.
The verdict, announced on Wednesday, overturns a suspended sentence handed down by a lower court earlier this year which ordered the defendant to pay about CHF300 ($329) and to cover a clean-up fee of CHF2,250.
The man daubed the façade of a Credit Suisse subsidiary in Geneva with red handprints, an action he said was done to protest against the bank’s investments in fossil fuels.
The latest ruling can still be challenged in the Federal Court.
Tennis matches
Last month another appeals court in western Switzerland reversed a ruling that had acquitted 12 activists of trespassing at a branch of the Credit Suisse bank in Lausanne.
The canton Vaud appeals court imposed fines of CHF100-150. The court argued that the activists could have used other means of protesting against alleged environmental abuses of the bank.
The group had staged tennis matches inside a Credit Suisse bank in Lausanne.
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