Complex sentence: Carrying a hip flask filled with alcohol in a public place is illegal in many locations in the United States due to open container laws which prohibit possession of an unsealed container of alcohol in public or within the passenger compartment of a vehicle.
Split into simpler sentences: Carrying a hip flask filled with alcohol in a public place is illegal in many locations in the United States due to open container laws. These laws prohibit possession of an unsealed container of alcohol in public or within the passenger compartment of a vehicle.