A simplex priest is ordained as a priest, but in exercising his priesthood, he's restricted in two areas. First, simplex priests can't preach at Mass. Second, simplex priests can't hear confessions.
The reasoning behind these restrictions lay in the 1917 Code of Canon Law. According to this code and understanding of the law, clerics had to be granted faculties to preach by their bishop. Further, bishops could give the faculty to hear confessions fully, limit a priest to a certain territory, or withhold them all together if priest didn't pass certain examinations.
In Blessed Father Solanus Casey's case, he went to the diocesan seminary at age 21. There, however, he struggled academically, especially in learning German and Latin. He was dismissed from the seminary and encouraged to enter a religious order if he wanted to become a priest. Undeterred, Blessed Casey entered the Capuchin order at age 31 and was ordained a priest in 1904. Due to his academic struggles, he wasn't granted the faculties of preaching and hearing confessions.
Some might wonder why we don't still have simplex priests today, especially with the shortage of priests in our country. A reason is that, in 1983, the Code of Canon Law changed. It's now understood that, while a bishop may limit or revoke preaching faculties, a priest receives them immediately upon his ordination. While a bishop still must grant faculties to hear confessions, this is understood more liberally in the current Code of Canon Law than in the former code.
Father Mayo is pastor of Holy Rosary Parish in Warrenton.