Senatus consultum ultimum

Senatus consultum ultimum ("Final decree of the Senate" or Final Act, often abbreviated SCU), more properly senatus consultum de re publica defendenda ("Decree of the Senate about defending the Republic") is the modern term (based on Caesar's wording at Bell. Civ. 1.5) given to a decree of the Roman Senate during the late Roman Republic passed in times of emergency. The form was usually consules darent operam ne quid detrimenti res publica caperet or videant consules ne res publica detrimenti capiat ("let the consuls see to it that the state suffer no harm"). It was first officially decreed prior to the fall of Gaius Gracchus in 121 BC, and subsequently at several other points, including during Lepidus' march on Rome in 77 BC, the Conspiracy of Catiline in 63 BC, and before Julius Caesar crossed the Rubicon in 49 BC. The senatus consultum ultimum effectively replaced the disused dictatorship, by removing limitations on the magistrates' powers to preserve the state. After the rise of the Principate, there was little need for the Senate to issue the decree again.

From around the year 500 BC, the dictatorship was the main measure of emergency power in the Roman Republic. In a senatus consultum, the Roman Senate would authorize the consuls to nominate a dictator who received imperium magnum, great power to act in a time of emergency (usually military) until the crisis was over (but no longer than half a year). The dictatorship marked the sole exception from the rules of collegiality and responsibility, meaning the dictator was not legally liable for official actions. This changed around the year 300 BC, when, against its very nature, the dictatorship was placed under the public provocatio, meaning that the Plebeian Council could be called to counter-act executive actions of the dictator. As a result, the practice was altered and later dropped altogether after 202 BC.

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