IDP in France?

It's not legally required in France, but it's a good idea to have one anyway - in case you're stopped by a non-English-speaking officer. They're very easy to obtain - just go to any AAA office. You'll pay $15-$20. I've made several driving trips in France and I always carry one.

Tom is correct. This is a case where it is better to have it and not need it rather than need it and not have it. If you get stop you do want to make it super easy for the officer so he can see that you are a cooperating tourist.

It is always a very, very good idea to have an IDP. Not only does it translate your license, but it also validates it. That can be helpful with rental agents as well as police officers.

In what language is the IDP translated? Or is it in multiple languages? There are 23 official languages in the European Union. Is it translated into all 23?

The IDP has 10 languages, including Russian, Chinese, and Arabic. (11, if you count the English page.) It also contains a list of the over 100 world nations in which it is accepted.

Since it is not 'required', what if I brought one that is recently expired by about a month? It would still translate my license.

If it is expired then it is no longer valid. And it would do no good in assuring the validity of your drivers license, which is sometimes helpful with rental agents or police.

The "tricky" of the IDP is that is has standardized numbered-coded fields and standardized driving categories (this last feature useful only for those driving caravans, trailers, large campers, trucks), making it easy to spot the critical information a police or other party might need. European driver's licenses, by the way, have now the same codification, reason by which they are easily understandable in other European countries.

Maybe not essential but what get's you more excited to travel than a visit to the AAA office!