Australian standards
Due to their higher light output, HID lamps must comply with a specific set of Australian Design Rules.
These include specifics as to light colour, proportions of specified light wavelengths (including blue wavelengths) and ultra violet (UV) emissions.
Self levelling systems and headlight washers are also required to off-set the increased risk of dazzling other drivers.
Vehicle manufacturers sometimes refer to HID lamps as Xenon or Bi-Xenon lamps. However these should not be confused with conventional incandescent bulbs that use xenon gas in their glass envelope. Queensland legislation
HID headlight conversions are not permitted under Qld legislation. However, it is not clear if other Australian states view the issue in the same way. If you operate in another state you should check requirements in your area.
Note also that Queensland's Dept. Transport and Main Roads (DTMR) advises that there is currently no legislation concerning HID conversion of driving lights.