The traditional date for the end of classical Roman law is 235 when the emperor Alexander Severus was murdered, or slightly later with the death of Modestinus, the last of the great known jurists. Thereafter, few original juristic books were written, and it is widely but not universally believed that a decline in legal standards began almost at once.
For many scholars there seems to exist a connection, sometimes simply implicit, between the failure of jurists to write new books, and a decline in legal standards. I should like to suggest there was a different reason for jurists ceasing to write new law books. They had already written them all! The claim that for the period, say fifty years, after around 235, all the law books had already been written seems extreme, but is easy to substantiate.
The End of Roman Juristic Writing
Available at: http://digitalcommons.law.uga.edu/fac_artchop/463