In theory, there may come a time when the Church might have to witness sacramental marriages that are not recognized by the state. Ordinarily speaking though, in most countries of the world at this time, the Church does not take part in witnessing a sacrament between two people who want the benefits of marriage from the Church but are unwilling to accept the responsibilities of marriage enjoined on them by the state. Certainly priests and deacons are unlikely to have anything to do with perpetrating legal and moral fraud by witnessing an illegal marriage performed for unjust reasons (e.g., withholding justly-owed taxes).
