The prosecution itself presented no difficulty: the evidence was overwhelming and the Crown had taken the extra precaution of suborning Emmet's defence attorney, Leonard McNally, for £200 and a pension.

[3] But when McNally announced that the trial was concluded because his client wished to call no witnesses nor "take up the time of the court", Plunket took to his feet to berate the prisoner.

As Solicitor General, Plunket was one of the Irish officials singled out for attack in a series of scurrilous letters published by the radical journalist William Cobbett in his weekly newspaper Political Register.

In 1822 he was reappointed to the office of Attorney-General for Ireland, since William Saurin (Attorney General 1807–22) was implacably opposed to Catholic emancipation, which the Crown now accepted was inevitable.

His tenure as Chancellor was not without controversy: opponents accused him of political partisanship, lengthy absences from work, and nepotism on a scale unusual even in an age when it was understood that officeholders took care of their relatives.

He lived in considerable state: Sir Walter Scott, who visited him at Old Connaught, left a glowing tribute to Plunket's charm and hospitality, and the excellence of his food and wine.