(a)
Law enforcement vessels may display a flashing blue light when engaged in direct law enforcement or public safety activities. This light must be located so that it does not interfere with the visibility of the vessel's navigation lights.
(b)
The blue light described in this section may be displayed by law enforcement vessels of the United States and the States and their political subdivisions.
Code of Federal Regulations
[CGD 80-158, 47 FR 16175, Apr. 15, 1982, as amended by CGD 90-032, 56 FR 33385, July 22, 1991]