Legality
Certain countries (e.g. Hungary and other European Union members) regulate possession and or use of night-vision devices. German law forbids such devices if their purpose is to be mounted on firearms. Citizens' access to Gen 2 and up is outlawed by adopting International Traffic in Arms Regulations into national legislation. Generation 2 and higher devices are classified as military/law enforcement purpose and espionage tools. In Iceland, the use of night-vision devices for hunting is prohibited, while there are no restrictions on the devices themselves.
New Zealand rescue helicopter services use several sets of 3rd-generation night vision goggles imported from the USA, and the country is required to restrict access to the equipment to comply with the strict regulations regarding their export. There are no prohibitions on the ownership or use of night vision equipment for shooting non-indigenous game animals, such as rabbits, hares, deer, pigs, tahr, chamois, goats, wallabies, etc.
Most U.S. states have no such bans. In California it is a misdemeanor to possess a device "designed for or adaptable to use on a firearm which, through the use of a projected infrared light source and electronic telescope, enables the operator thereof to visually determine and locate the presence of objects during the nighttime.". This essentially covers scopes using Gen0 technology, but not the subsequent generations. There was an effort in 1995 to further expand restrictions to forbid night vision devices that did not incorporate a light source, but it did not become law.
Read more about this topic: Night Vision Device