Armand Brette, in his study of the boundaries and territorial divisions of France in 1789, published in 1907, writes with some amusement about the controversies surrounding the existence of this principality, and for his part concludes that the sovereignty of Bidache was real. He points out that having justice rendered without appeal is precisely an unequivocal sign of sovereignty, and arguably the very definition of it.

Historical research became far more precise with the successive work of the two leading specialists of the House of Gramont, Jean de Jaurgain and then Raymond Ritter. The volume signed by both authors, completed by the second after the death of the first and published in 1968, contains a detailed appendix devoted to this legal question, and was able to draw on a doctoral thesis in law dedicated to the subject by Jean Labrit in 1939.

Raymond Ritter likewise concludes very clearly that a genuine sovereign power existed over Bidache.