Legality review is a form of appeal against municipal decisions regulated in Chapter 13 of the Local Government Act (2017:725). In a legality review, the Administrative Court examines whether the appealed decision is in conflict with any act or other statute. If the decision is found to be unlawful, the court shall annul the decision. However, the court may not replace the unlawful decision with a new one. When the court examines cases concerning legality review, it shall consist of one legally qualified judge and two special members with good knowledge of municipal operations.
You can read more about judicial review on the Swedish Courts website (in Swedish).