In the flats where I live, the car parks are surveillled by a private security firm. If I have undersood correctly here, if someone parks in a resident's parking place, it is necessary to contact your concierge, who can in turn contsact the security firm to come take the car away, fine them. Otherwise ask your Regie more about this.  

It looks like Department 31, which is Haute Garonne. A very long way from home then.

Not locally like us, Dept. 74 - there is probably not an awful lot you can do about this, except fume!

This happened to me once. After waiting for a while, I phoned the police. All they said is that I couldn't park my car behind if that prevented the other car from leaving. That is, that I should look for a parking place for my own car for that night. And that they would no nothing about it. Their only reply to my WTF? reaction was that if I wasn't happy about that, I could pass the following day by the police office and make a formal denunciation. Probably useless (they did not say that, but that was my impression).

On the other hand, I know at least one person whose car was towed away in Geneva because he parked it in a private spot when everything was completely covered in snow and it was impossible to see the yellow marking. 

You legally have the right to have it towed.

The only problem with that is actually having it towed is not always simple and you'll have to pay the cost of it. Getting back the money often doesn't worth the time and energy you'll need.

Another solution is to ask to you local court a decision of "interdiction juridique de stationnement".

In that case, you'll have to put a sign on your parking spot. You'll then be able to simply lodge a compaint any time somebody is parking on your space and they'll receive a fine (and yes, nowadays, they do cross the border to France in case you are wondering).

In other words, it's complicated and doesn't worth your time if it only happened once. Then it will always be time to think about more "serious" measures to be taken.

Regarding the license plate with the 31 designation: several years ago, the French changed the license plate procedure. You can now get license plates from any departement you want. If you are form Paris but live in Ferney because of work, you can still get a 75 plate. Or, since every knows (wink) that Parisian drivers are crap and therefore get more tickets when found elsewhere because every one recognizes them by their 75, they can decide to get a 74, because that's where are the cool kids live. ;)

I lived in an apartment building near the Petit Saconnex Mosque with my own parking spot. Every day at lunchtime and especially during their holy days, our parking lot would be packed with cars for people who were going to the Mosque for prayer. They would never understand when I, or others, would be upset that they had parked in our spots. I took pictures of their license plates as they left/returned from prayers. I would park them in. Once or twice, I would let air out of their tires.

Maybe it's not "sactioned" to block their way, but I think the hassle for them would be equal to your hassle, so I had no problem doing it.

But, yeah, mean people suck.

Try taking off the licence plates without telling the sods. It won't be long before they are stopped by the police either in CH or France for sure at the border.  And then they have to go get another set at their own expense.

If they do notice their plates are missing, then you ask for a swap of €50.  Just get a photo of the car with & without plates in case they take revenge later, and let them know that you have the photos.

I am surprised police didn't want to do anything. If you prove that you have a right on this parking space (ownership or lease), police is due to contact first the owner usurper with its database. If police is unable to get in touch with the usurper, it should remove the car. It happened like this in my building.

You could take bright lipstick and leave a message on their window...!  It's a pain to remove.  You would of course be breaking the law... probably.

I think stealing number plates is too far (does theft and blackmail counter someone taking a parking space??), but certainly let the air out of their tires. Boxing is a good idea, but I tend to prefer to leave juuuuuust enough space, so they can get out, but they have to do basically a 100 point turn.

One thing that was done to us as school so we wouldnt drive in, was using pritstick or some other glue stick to attach a "sign" to their car. Once dried, and without the right tools, it is a massive pain in the arse to get rid of and often left reminance on the window. I would go A3 on their front windshield.

Though I'm not sure why people are surprised about the police... that is them in a nutshell.

With regards to the feeling of them getting off the hook. I'd hazard a guess that is impotent rage caused by not acting while you had them or their car in your sights.

Annoyance is much better than criminal response. When people cut me up on my bike or swerve into the bike lane, I will get in front of them, and then not move for about 5-10mins depending on how busy I am, with the fattest smile on my face. Works like a blooody charm... at annoying them. No idea if it stops them from doing it.

use a baseball bat next time ...