Canonical Penance:
The specified penance, corresponding to the nature and gravity of the sin, prescribed by confessors in the sacrament of penance. These penances were listed in penitential books. Celtic in origin, the earliest canonical lists are ascribed to St. Patrick and date from the fifth century. In time the practice spread throughout Europe. The best known penitential book is that ascribed to Archbishop Theodore of Canterbury (602-90).
Modern Catholic Dictionary. (Fr. John Hardon, S.J.)
catholicculture.org/culture/library/dictionary/index.cfm?id=32300
Canonical penance (2nd to 6th centuries) …However, canonical penance did not last for several reasons. Since it could only be received once in a lifetime, it gave rise to “deathbed penance” and even “deathbed baptism” for the many who did not want to commit to a life of Christian conversion but wanted to commit to Christ as a final option. Second, the ritual became impractical as more and more people were becoming Christian and the tangible experience of common-union waned considerably. Finally, fewer people were willing to endure such a process when other options became available.
rpinet.com/ml/3110reco.html
Originally for idolatry, adultery, and homicide. One that did not perform the canonical penance could be kicked out of the Church.
Is this a homework assignment?