A method of detecting absence of a parking right for vehicles parked at a parking facility, the parking facility comprising an entrance, an exit and a cash-out machine; a camera being associated with the entrance, the exit without an exit barrier, camera, and near-field communication technology and the cash-out machine for obtaining a retro-active parking right near the end of a parking action, based on an entrance logged by the camera the method making use of a database comprising active parking rights as well as retro-active parking rights obtained via an after-payment method, the method comprising the steps of: 1) in a first enforcement action: identifying one or more vehicle present at the parking facility by retrieving unique identifiers of one or more vehicles; 2) for each of the identifiers, querying the database to retrieve a subset of vehicles, the subset comprising those vehicles that do not have an active parking right for parking at the parking facility; 3) in a second enforcement action: identifying at least one vehicle of the subset of vehicles as absent from the parking facility to retrieve a subsubset of vehicles comprising those vehicles of the subset that are absent during the second enforcement action, the second enforcement action performed at a later instance than the first enforcement action; 4) for each of the identifiers in the subsubset, querying the database to retrieve those vehicles of the subsubset that have not obtained a retro-active parking right in between performing the first and the second enforcement action; 5) marking the group of vehicles retrieved in step 4). the parking facility comprising an entrance, an exit and a cash-out machine; a camera being associated with the entrance, the exit without an exit barrier, camera, and near-field communication technology and the cash-out machine for obtaining a retro-active parking right near the end of a parking action, based on an entrance logged by the camera the method making use of a database comprising active parking rights as well as retro-active parking rights obtained via an after-payment method, the method comprising the steps of: 1) in a first enforcement action: identifying one or more vehicle present at the parking facility by retrieving unique identifiers of one or more vehicles; 2) for each of the identifiers, querying the database to retrieve a subset of vehicles, the subset comprising those vehicles that do not have an active parking right for parking at the parking facility; 3) in a second enforcement action: identifying at least one vehicle of the subset of vehicles as absent from the parking facility to retrieve a subsubset of vehicles comprising those vehicles of the subset that are absent during the second enforcement action, the second enforcement action performed at a later instance than the first enforcement action; 4) for each of the identifiers in the subsubset, querying the database to retrieve those vehicles of the subsubset that have not obtained a retro-active parking right in between performing the first and the second enforcement action; 5) marking the group of vehicles retrieved in step 4). 1) in a first enforcement action: identifying one or more vehicle present at the parking facility by retrieving unique identifiers of one or more vehicles; 2) for each of the identifiers, querying the database to retrieve a subset of vehicles, the subset comprising those vehicles that do not have an active parking right for parking at the parking facility; 3) in a second enforcement action: identifying at least one vehicle of the subset of vehicles as absent from the parking facility to retrieve a subsubset of vehicles comprising those vehicles of the subset that are absent during the second enforcement action, the second enforcement action performed at a later instance than the first enforcement action; 4) for each of the identifiers in the subsubset, querying the database to retrieve those vehicles of the subsubset that have not obtained a retro-active parking right in between performing the first and the second enforcement action; 5) marking the group of vehicles retrieved in step 4).