It had nothing to do with the fact Amazon isn't French, from what I understand. The change to the law will affect the smaller French retailers like FNAC (also accused of dumping) more, they're already barely able to compete with Amazon that's the #1 online retailer in France (70% of the market, all products combined). The law would only affect their sales of books. It's really the bookstores and the French bookstore culture the revised law seeks to protect, for a few more years.

Its critics say it won't work, that it will have nearly no effect on the profits of Amazon.fr and that it might only convince the French to buy e-readers at last (even the Lang law doesn't regulate the price of e-books), a trend they've resisted so far.

From articles I've read, a few constitutional lawyers believe the law will be deemed unconstitutional as it doesn't respect some provisions about the free market.

A "online" tax for books was considered, but rejected. From what I understand they could not legally forbid a retailer from absorbing the tax for the consumer, so the retailer could simply cut their profit margin to keep the book prices unchanged.

Personally if this finally forces the French publishers to sell their e-books for a reasonable price, I wouldn't mind. I'm all for nostalgia about the small bookstores which I already miss, but since the apparition of the e-book format I no longer think the publishers are justified to believe it's the disappearance of the bookstores that will greatly harm the viability of French literature. They were right to think so when the great surfaces that sold only recent best-sellers were killing the bookstores, but now the online retailers let consumers access to their whole catalogs right away, without waiting weeks for a rarer title to be ordered etc.

Their real problem is that they're about to lose almost completely the lucrative market of the classics, a very large percentage of the works from the golden age of French literature have already fallen in the public domain and the great writers from the first half of the 20th century will follow sooner than later (some of which are already available, those who died before the end of WWII like Proust). They've averted this in the last decades, because books still had to be printed, and more recently because the French still don't buy e-readers, which is not the case already for Québécois, for instance. The French publishers won't be able to delay the spread of e-books in France for much longer. The publishers have done it by keeping the offer low, and very expensive. But already they've started to speed things up to release their back catalogs, including titles long out of print and no longer commercially viable as physical releases, while at the same time they keep slowing things down with new releases, either releasing the e-book a year after the original release, or selling them right away, but for a higher price than the physical book (!). They also stupidly release classics for nearly the price of the paperback. E-books for e-book, it's idiotic to pay Gallimard 7-10 Euros for Les Trois Mousquetires, when you can get a good edition of the complete works of Dumas for 4$ from a digital-only publisher, or else for free if you don't mind individual titles and often less professional e-books...