France, April 21 -- French President Emmanuel Macron's announcement of a new tax on used book sales to protect new books is the latest proposal from a government with a history of intervening in the publishing industry to keep it afloat.

While the used book market is on the rise in France, the Emmaus charity - a third of whose online revenue comes from books - is raising the alarm over unfair competition from online retailers.

Macron has proposed adding a tax to used book sales, which he says would help publishers, authors and translators.

Speaking at the annual Paris book fair last weekend, Macron said that used books - most of which are sold on major online retail platforms like Amazon - posed a competitive threat to the price of new...