Can a justice of the peace, who is a lawyer, practice criminal law in superior courts, or in any county outside his own county?
18 Baylor L. Rev. 200 (1966)
JUDGE ACTING AS A LAWYER - EMPLOYMENT
Although a justice of the peace, who is a lawyer, may practice criminal law in superior courts, or in any county outside his own, where the matter has not been before him in his capacity of J.P., it would be preferable for him to refrain from that practice even though no statute or Canon expressly prohibits it.
Canon 6.
The committee is of the opinion that the foregoing question should be answered "Yes". A majority of the committee members are of the opinion that such question should be answered "Yes" only where the matter has not been before him in any manner in his capacity of justice of the peace, and are of the further opinion that it would be highly preferable for said justice of the peace to refrain from such practice even though there is no statute or Canon which expressly prohibits him from doing so. (6-1)
Tex. Comm. On Professional Ethics, Op. 16 (1948)