Even were Brutus not a traitorous opportunist, to whom Caesar was greatly beneficent, the idea that Caesar was a tyrant is absurd to me, if we consider the state of Rome, he was a necessity.
But even if we consider him a tyrant, there is no support in Catholic tradition for tyrannicide. Even on a practical level, well here is Aquinas:
Quote:
For it may happen that those who act against the tyrant are unable to prevail and the tyrant then will rage the more. But should one be able to prevail against the tyrant, from this fact itself very grave dissensions among the people frequently ensue: the multitude may be broken up into factions either during their revolt against the tyrant, or in process of the organization of the government, after the tyrant has been overthrown. Moreover, it sometimes happens that while the multitude is driving out the tyrant by the help of some man, the latter, having received the power, thereupon seizes the tyranny. Then, fearing to suffer from another what he did to his predecessor, he oppresses his subjects with an even more grievous slavery. This is wont to happen in tyranny, namely, that the second becomes more grievous than the one preceding, inasmuch as, without abandoning the previous oppressions, he himself thinks up fresh ones from the malice of his heart. Whence in Syracuse, at a time when everyone desired the death of Dionysius, a certain old woman kept constantly praying that he might be unharmed and that he might survive her. When the tyrant learned this he asked why she did it. Then she said: “When I was a girl we had a harsh tyrant and I wished for his death; when he was killed, there succeeded him one who was a little harsher. I was very eager to see the end of his dominion also, and we began to have a third ruler still more harsh—that was you. So if you should be taken away, a worse would succeed in your place.”
If the excess of tyranny is unbearable, some have been of the opinion that it would be an act of virtue for strong men to slay the tyrant and to expose themselves to the danger of death in order to set the multitude free. An example of this occurs even in the Old Testament, for a certain Aioth slew Eglon, King of Moab, who was oppressing the people of God under harsh slavery, thrusting a dagger into his thigh; and he was made a judge of the people [Judges 3:14 ff].
But this opinion is not in accord with apostolic teaching. For Peter admonishes us to be reverently subject to our masters, not only to the good and gentle but also the froward [1 Pet 2:18-19]: “For if one who suffers unjustly bear his trouble for conscience’ sake, this is grace.” Wherefore, when many emperors of the Romans tyrannically persecuted the faith of Christ, a great number both of the nobility and the common people were converted to the faith and were praised for patiently bearing death for Christ. They did not resist although they were armed, and this is plainly manifested in the case of the holy Theban legion.” Aioth, then, must be considered rather as having slain a foe than assassinated a ruler, however tyrannical, of the people. Hence in the Old Testament we also read that they who killed Joas, the king of Juda, who had fallen away from the worship of God, were slain and their children spared according to the precept of the law” (2 Sam 14:5-6).