There are few terms more misused in the antique business than "attributed to". Most major auction houses now have a fairly high bar before they decide to add the "attributed to" label. Many dealers, however, set the bar ridiculously low. Similarity to a signed example, alone, is never enough to make an attribution.
Take, for instance, the fruit-wood desk chair shown above. I purchased it a Hotel Drouot a few years ago. It is circa 1820-1830 from both form and construction. Now compare it to the black and white photograph of a chair made by J.J. Werner for the Tuileries Palace during the Restauration. The stamped Werner chair is gilded and more complex, but it is known that Werner frequently used fruit-wood in his chairs and furniture. Note the carving on the sides of the back stiles and the carved design on the sub-pediment crest. Obviously, these chairs were either made by Werner or by two makers familiar with this specific design. So, can the unsigned chair be attributed to Werner?
Some additional research yielded a similar image from Mesangere's influential Meubles et Objets De Gout (see below). These Mesangere folio plates of furniture designs were issued from the 1790s until the 1830s. While they certainly inspired many furniture makers, it is certain that Mesangere himself was inspired by some of the existing production of the leading furniture makers in Paris.
It is therefore impossible to know if the Mesangere design inspired Werner or vice versa. However, it is clear that the fruitwood chair and the Tuileries chair share more design elements with each other than either does with the Mesangere design. As the Tuileries chair was in a fairly public space and therefore would have been widely viewed, it is not an unlikely scenario that a visiting noble saw the Tuileries chair and had his preferred menuisier make a copy.
My conclusion, the fruit-wood chair is in the style of Werner, but cannot be definitively attributed to him.
Mesangere Chair Design