SatNav and GPS systems that show speed cameras are illegal
 

How enforceable is this law? Do police ask to see your smartphone when stopped? Does anyone have any first hand experience with this?

Huh?
What law?
Experience with what?

No, and when you get that speeding violation letter from Italy six months later it doesn't ask to see your cellphone, either.

In France locations of speed traps are illegal for all navigation devises. No new GPS units now have camera locations located and in fact they have only safety zones. You will never know where mobile cameras will be placed.
It seems the laws says the police in France can inspect the GPS unit. Fines are higher than speeding fines if you are caught.

For example I have a GPS app on my iPhone that does show camera locations. So how would police know if it's on my iPhone?

In Germany, it is LEGAL to use GPS/SatNav devices that show the (typically stationary) locations of speed cameras and warn you if you are over the limit. Regardless if it's done via an app on your smartphone or a GPS navigation device like TomTom.
It is/was ILLEGAL in Germany to use radar detectors that actually pick up the radar signals from a (typically portable) radar gun, though.

The fines are heavy in France if you have radar camera positions marked on your GPS or navigational unit. What Michelin now shows on their maps are <i>danger zones</i> which you may in interpret as speed cameras.

I just hope that when you use whatever you use to avoid those "danger zones" or speed camera locations that you do not run into ME as a result.

Radar is illegal where I live also for that purpose. However, GPS is legal because the city doesn't try to hide the location of speed cameras, they publish lists online and in Maryland, at least, there are always signs telling you when you are entering a speed camera enforcement zone. There really is no excuse to complain they are unfair, but people do (people who are speeding and, of course, also ignore the signs). The signs aren't tricky or hidden, you just have to know to look out for them and not daydream.

I dont' think they have signs warning you in France, but I've never seen any but major highways. If GPS is illegal, I would guess they dont' post signs, either.

Why would anybody need to be informed of where the speed cameras are unless they are dangerous drivers? I would certainly hope that they would be prosecuted to the full extent of the law.

Unfortunately, so of you are lucky, because even though you will receive a huge fine for speeding well over the speed limit, the gendarmerie can only confiscate and cancel French drivers licences.

Thanks everyone for your comments, My intention is not to speed, drive dangerously. I only want to use my iPhone as a portable GPS while driving through Europe. Unfortunately it does show speed cameras and I don't want my iPhone confiscated or worse. This is why I asked how is the law enforced?

Most of the driving laws (seatbelts, orange reflective vest, etc.) are only enforced if you are stopped for some other reason. Additional investigations are generally based on whether you are being cooperative or not.

If your maps show locations of speed cameras it will mean your maps are out of date. That would be a big worry for me.

As far as I know, devices locating radars are illegal in Switzerland and fines are quite high.

I've checked the TomTom website. And aside from the aforementioned issues in France, there is no mentioning of any other European countries which would have any restrictions or laws against using SatNav/GPS-based speed camera localization. Obviously, I cannot guarantee that this information is thoroughly correct.
Nevertheless, it is a pretty accurate way to get warned of speed cameras as both the maps in good apps as well as the TomTom devices or similar get updated online regularly and also use drivers' input to mark new camera positions.
FWIW, the police even gives local radio stations the locations of portable speed cameras here - as the intention is that people drive slowly in dangerous areas like in school zones or similar.

One thing that you might not know is that every speed camera in France is preceded by a sign telling you of its existence, which might be anywhere ahead between 100 meters (urban areas) and 2-4 kilometres (autoroutes). They were going to remove the warning signs, but it was decided that prevention is always better than repression.

The signs do not warn you about the placement of mobile ones so it pays to keep within the limits at all times.

<i>One thing that you might not know is that every speed camera in France is preceded by a sign telling you of its existence, </i>

To say that every speed camera has a warning sign is inaccurate. Many, many cameras have no warning at all and, as noted above, there are always the mobile cameras.

The warning signs that were in place were to be removed. Those who argued that signs act as a deterrent prevailed in keeping them in place. Those in the government who are more interested in the revenue fines produce, were successful in limiting, if not eliminated, signs for new cameras.

<i>For example I have a GPS app on my iPhone that does show camera locations. So how would police know if it's on my iPhone?</i>

Without inspecting your device, they have no way of knowing. You probably won't know that you've gotten a ticket until several weeks later when you get a letter from the car rental agency saying that you owe a fine plus a service fee.