Almost every driver has waved another driver on at one time or another.
It happens all the time at intersections or in heavy traffic. You may find yourself looking directly in the eyes at some poor soul who just wants to find a break in the traffic and make his or her way home from work. You pause your car and give a little wave, signaling the other driver to move ahead.
That makes you a nice person -- but it also opens you up to legal liability every time you do it. If another car comes along and zips ahead, somehow hitting the car you just waved into traffic, you could be held partially responsible for the accident.
The same is true, naturally, if you happen to be the driver who gets waved into traffic and you end up in a wreck. The driver who waved you ahead might be partially liable for any injuries you suffer.
Part of the questions that juries have to consider when they look at a car accident lawsuit, is whether or not a defendant has any legal duty of care in a situation. You automatically have a duty of care to be a responsible driver when you're behind the wheel. A jury may decide that you voluntarily took on some additional responsibility for another driver the moment that you decided to wave that driver into traffic.
On the other hand, because Louisiana uses the concept of comparative negligence, juries have to decide exactly how much responsibility each party in an accident has to bear. In that kind of situation, it may not be easy to resolve and could result in a lot of legal wrangling in court.
Unfortunately, there's really only one solution to the issue. Even if it goes against your instincts, don't try to help another driver along by waving him or her into traffic -- and don't accept another driver's wave as assurance that the way is really clear.