Revised Penal Code, Art. 78

When and how a penalty is to be executed. -No penalty shall be executed except by virtue of a final judgment. A penalty shall not be executed in any other form than that prescribed by law, nor with any other circumstances or incidents than those expressly authorized thereby. In addition to the provisions of the law, the special regulations prescribed for the government of the institutions in which the penalties are to be suffered shall be observed with regard to the character of the work to be performed, the time of its performance, and other incidents connected therewith, the relations of the convicts among themselves and other persons, the relief which they may receive, and their diet. The regulations shall make provision for the separation of the sexes in different institutions, or at least into different departments, and also for the correction and reform of the convicts.