Federal Regulations for Headlamp Bulbs
Federal Motor Vehicle Safety Standard 108 ParagraphS7.5(b) specifies that any replaceable bulb headlamp system shall be designed to conform to the appropriate photometric requirements of the standard using any light source of the type intended for use in such system.  Paragraph S7.7 specifies that each replaceable light source shall be designed to conform to the design specifications furnished with respect to it pursuant to part 564.  The table below enumerates the light bulb types approved by the US DOT for use in motor vehicles, and provides their major design characteristics.
Critical Note:
1. Any bulb not fully meeting one of the descriptions below, and not listed in DOT Docket NHTSA 98-3397 is not legal.
2.  Each light source has a maximum permissible actual wattage at 12.8v. This is in most cases higher than the nominal wattage printed on the bulb base and packaging. Each light source also has a nominal output (lumens) requirement, with a +/- tolerance.
3.  Each light source entry also specifies the allowable glass coatings, if any (in most cases, none.).
All of this means:
Overwattage bulbs, most blue-glass bulbs, and "HID kits" and base-adapted HID bulbs don't comply with Federal law.

 
 

Part 564

Replaceable Light Source Types

 
Allowable Bulb Types Trade Name Max. Watts Luminous Flux (lm)

Coating, filtering, tinting

 Remarks
Primary Alternative
9500 9500 36.5 2800 ± 400 none HID
D2R D1R D2R 38 D2R 2800 ± 450 Black stripes. HID
D1R D1R 2800 ± 450 Black stripes.
D2S D1S D2S 38 D2S 3200 ± 450 none HID
D1S D1S 3200 ± 450 none
H1 H1 65 1410 ± 210 none Single axial filament
H3 H3 65 1310 ± 195 none Single transverse filament
H7 H7 55.6 1350 ± 12% Black cap Single axial filament
H8 H8 41 730 ± 110 Black cap Single axial filament
H9 H9 70 2000 ± 240 none Single axial filament
H11 H11 59 1250 ± 150 Black cap Single axial filament
HB1 9004 Low Beam 50 700 ± 15% Black cap Dual transverse filaments
High Beam 70 1200 ± 15%
HB2 9003 Low Beam 65 910 ± 10% Black cap Dual axial filaments
High Beam 72 1500 ± 10%
HB3 HB3A 9005 70 1700 ± 12% none Single axial filament 
HB3A has straight base
HB4 HB4A 9006 60 1000 ± 15% Black cap Single axial filament
HB4A has straight base
HB5 9007 Low Beam 60 1000 ± 15% Black cap Dual axial filament
High Beam 70 1350 ± 15%
HIR1 9011 70 2300 ± 15% Durable infrared coating Single axial filament
HIR2 9012 60 1700 ± 15% Durable infrared coating Single axial filament