Limitation of the Dictatorship

The old unity and plenary legal power of the -imperium- were retained
longer in the case of the dictatorship than in that of the consulship.
Although of course as an extraordinary magistracy it had in reality
from the first its special functions, it had in law far less of a
special character than the consulate. But it also was gradually
affected by the new idea of definite powers and functions introduced
into the legal life of Rome. In 391 we first meet with a dictator
expressly nominated from theological scruples for the mere
accomplishment of a religious ceremony; and though that dictator
himself, doubtless in formal accordance with the constitution,
treated the restriction of his powers as null and took the command
of the army in spite of it, such an opposition on the part of the
magistrate was not repeated on occasion of the subsequent similarly
restricted nominations, which occurred in 403 and thenceforward very
frequently. On the contrary, the dictators thenceforth accounted
themselves bound by their powers as specially defined.

Restriction as to the Accumulation and the Reoccupation of Offices

Lastly, further seriously felt restrictions of the magistracy were
involved in the prohibition issued in 412 against the accumulation
of the ordinary curule offices, and in the enactment of the same date,
that the same person should not again administer the same office under
ordinary circumstances before an interval of ten years had elapsed, as
well as in the subsequent regulation that the office which practically
was the highest, the censorship, should not be held a second time
at all (489). But the government was still strong enough not to be
afraid of its instruments or to desist purposely on that account