Many of the political subtleties of the Second Settlement seem to have evaded the comprehension of the Plebeian class.

When Augustus fails to stand for election as consul in 22 BCE, fears arise once again that Augustus is being forced from power by the aristocratic Senate.

In this year there is a food shortage in Rome that sparks panic, while many urban plebs call for Augustus to take on dictatorial powers to personally oversee the crisis.

After a theatrical display of refusal before the Senate, Augustus finally accepts authority over Rome's grain supply "by virtue of his proconsular imperium", and ends the crisis almost immediately.

Nevertheless, there are some who are concerned by the expansion of powers granted to Augustus by the Second Settlement, and this comes to a head with the apparent conspiracy of Fannius Caepio and Lucius Lucinius Varro Murena.

In early 22 BCE, charges are brought against Marcus Primus, the former proconsul (governor) of Macedonia, of waging a war on the Odrysian kingdom of Thrace, whose king is a Roman ally, without prior approval of the Senate.

He is defended by Murena, who tells the trial that his client had received specific instructions from Augustus, ordering him to attack the client state.

Later, Primus testifies that the orders came from the recently deceased Marcellus.

Under the Constitutional settlement of 27 BCE such orders, had they been given, would have been considered a breach of the Senate’s prerogative, as Macedonia is under the Senate’s jurisdiction, not the Princep’s.

Such an action would have ripped away the veneer of Republican restoration as promoted by Augustus, and exposed his fraud of merely being the first citizen, a first among equals.

Even worse, the involvement of Marcellus provided some measure of proof that Augustus’s policy was to have the youth take his place as Princeps, instituting a form of monarchy—accusations that had already played out during the crisis of 23 BCE.

The situation is so serious that Augustus himself appears at the trial, even though he has not been called as a witness.

Under oath, Augustus declares that he gave no such order.

Murena, disbelieving Augustus’s testimony and resentful of his attempt to subvert the trial by using his auctoritas, rudely demands to know why Augustus has turned up to a trial to which he has not been called; Augustus replies that he has come in the public interest.

Although Primus is found guilty, some jurors vote to acquit, meaning that not everybody believes Augustus’s testimony.

Then, sometime prior to September 1, 22 BCE, a certain Castricius provides Augustus with information about a conspiracy led by Fannius Caepio against the Princeps.

Murena is named among the conspirators.

Tried in absentia, with Tiberius acting as prosecutor, the jury finds the conspirators guilty, but it is not a unanimous verdict.

Sentenced to death for treason, all the accused are executed as soon as they are captured without ever giving testimony in their defense.

Augustus ensures that the facade of Republican government continues with an effective cover-up of the events.

Augustus now returns membership in the Senate from nine hundred to six hundred.

Agrippa is soon back in Rome to act on behalf of the emperor, who himself leaves for the East in 22.