Laser site for rifles?

What are the laws governing this? How powerful are they? What's the longest distance they are effective?

I will leave those laws to the ones with JD after their name but as far as laser I have been using a crimson trace Rail master on an AR platform absolute daylight best is 20 yards but in those lower light and night have it set to 90 o 110 yards due to my bore axis issues so to answer range dot gets a little small for my eyes beyond that

Depends on what game, where, etc. For hogs it's pretty much game on for anything. Seems like I read for Deer, lasers are illegal.

I've had better luck seeing green vs red in the daytime.

Charlie