More and more states in the U.S. are passing laws that require drivers to leave 3 feet of space between their cars and cyclists when they pass them. Recently the State of California also passed a similar law, but it was subsequently vetoed by Governor Brown, despite huge support from cyclists, because this particular law required cars to slow down to 15 mph if they couldn't give cyclists enough space when passing, and he felt this might cause rear-end collisions.
We had a discussion about the concept of 3 foot (of course in Canada this would be 1 meter) passing laws at one of our last Committee meetings. Some of us agreed that such a law would help cyclists to feel safer. Many seasoned cyclists have some harrowing stories to tell about being clipped or almost hit by cars that were getting too close, and some didn't live to tell their stories. At least a law like this would hopefully make drivers more aware of the fact that they are legally required to keep a certain distance.
There are several problems with a law like this however.
First of all, it's pretty much impossible to enforce. Nobody's going to be able to measure the distance between a car and a cyclist after the fact, unless there's a clear video recording or photograph taken at the right moment, and from the right angle.
Also, this is in my opinion a law that may work for 'experienced' cyclists only, not for 'cyclists of all ages and abilities'. Now that more cycling advocates realize that they need to advocate for the needs of all cyclists - not just the strong and fearless - there are still quite a few who think this is a law that makes sense. An adult, 'experienced' cyclist, may feel totally comfortable with a car passing at 3 feet distance at 60 km/h when he's cruising along himself at 30 km/h, but the same may not be the case for an elderly woman for example, who bikes at a much slower speed and thus a higher speed differential, and may not have the same sense of balance anymore, or a young child, who may not always bike in a very straight line.
Another important issue that I have with this law, is that it does not take into account the kind and size of vehicle, nor its speed. It can be pretty scary to have a large truck pass by, especially with a trailer behind, at 3 feet distance, and especially if that truck is going 100 km/h, or even 50 km/h.
There does seem to be strong support among cyclists for some type of passing law, and in the absence of a better option, something is better than nothing I suppose.
It's obvious that the better option that we should be aiming for is of course separated infrastructure on busier and higher speed roads.