Is it permissible, in Islamic law, for the traffic department to confiscate and sell motorcycles because their owners do not possess licenses and official documents? What is the ruling on selling what one does not own in this case? Is this considered usurpation (ghasb)? And what is the ruling on those who buy these motorcycles from the state or from those who bought them from the state?

Money confiscated rightfully can be seized and sold by the government, and it is permissible to buy it. As for money confiscated unjustly, the basic ruling is that it is not permissible to sell or buy it because it still belongs to its owner. However, if it is impossible to return the money to its owner, Sheikh Ibn Uthaymeen has issued a fatwa (definition) permitting its purchase from the government, and it is commendable for the buyer to donate the difference if he buys it for less than its real value.