Historian Joyce E. Salisbury points out that "The random nature of the persecutions between 64 and 203 has led to much discussion about what constituted the legal basis for the persecutions, and the answer has remained somewhat elusive..." Candida Moss says there is "scant" evidence of martyrdom when using Roman Law as the measure. Historian Joseph Pescia asserts that the first evidence of Roman law concerning Christians is that of Trajan. T. D. Barnes and St. Croix both argue there was no Roman law concerning the Christians before Decius and the third century; Barnes agrees that the central fact of the juridical basis of the persecutions is Trajan's rescript to Pliny; after Trajan's rescript, (if not before), Christianity became a crime in a special category.