White LED okay shining from the rear?

[turbodish]

Any turn signal color is legal, as long as it can be clearly visible and understood which way you are turning from a min distance of ~30m. There is no law stating the color of turn signals. But as stated before not recommended.

Wrong. The HTA clearly defines which color lamps must be displayed to the front and rear of a vehicle, and which colors may not. With respect to the rear of a vehicle, no white light can be displayed, whether for use in the context of a turn signal or in a running light makes no difference.