Cicero not only argued that the law shouldn't apply in certain circumstances, but later circumvented the law after he became consul of Rome in response to what's been called "the Catiline conspiracy" (in fact the second Catiline conspiracy, but it's the second one that's most remembered--Sallust authored a work about the conspiracy).
Roman senator Lucius Sergius Catilina, other former senators, and some disaffected followers of the former dictator Lucius Cornelius Sulla (I rejoice in the names of the ancient Romans--I'm not sure why) conspired to assassinate Cicero and his co-counsel Gaius Antonius Hybrida and gain power for themselves. Catilina was an unsuccessful candidate for election as consul the year Cicero won.
Long story short, as they say, Cicero became aware of the plot and those conspirators at hand were rounded up. Cicero convened the Senate, which sanctioned the summary execution of the five conspirators captured. Catilina and most of his army of rebellion were killed subsequently in battle.
The conspirators were entitled to trial under the law, however, before execution and were deprived of it by action of Cicero and the senate, over the objections of Gaius Julius Caesar, interestingly enough.
Cicero thought that he'd saved the Republic by his prompt action, and was fond of reminding Romans that he'd done so. It's likely he did. But it's been thought by some that if he saved it he saved it by violating the law.
It can be maintained that the situation was one
inter arma--in the midst of a clash of arms, and the extremity of the circumstances justified the "muting" of the law, and Cicero was acting in accord with his own maxim. But Cicero as consul wasn't acting as Cicero the lawyer, defending a client against the charge of murder. Cicero the lawyer, had he been retained by the conspirators, would have joined Caesar in objecting to the executions without trial as contrary to law. Cicero the consul was violating the law, though he was wise enough to obtain the senate's consent to the executions and so couldn't be said to have done so himself.
Every lawyer must struggle with the fact that a lawyer's duty may require him/her to persuade others that the law shouldn't be applied in certain circumstances or should be interpreted in a way that precludes its application. For some the struggle is short-lived. Speaking for myself, the struggle is difficult, and lately I've been disgusted by the conduct of some of my brothers and sisters at the bar here in our Great Union.
But I'm not addressing that struggle here. Obviously I'm a Ciceronian; I admire him greatly. But I question whether the rule of law should be ignored even in times of war or crisis--whether certain laws, at least, should be disregarded. Here in the U.S. Thomas Jefferson and Abraham Lincoln threw the rule of
habeas corpus out the window as it suited them. Woodrow Wilson was a marvel, a pioneer, in restricting civil liberties during WWI. In what sense was disregarding the law proper? Is there any evidence that doing so achieved anything?