The phrase "in exercise of" is correct and can be used in written English.
It is typically used in a legal context to refer to the action of exercising a power, authority, or right. For example, you might say: "The local government issued the emergency order in exercise of its power under the relevant law."
Legally, the pardon is granted by the crown, on the advice of the justice secretary, in exercise of the royal prerogative of mercy.
Asked whether the central government, in exercise of its powers of eminent domain, could acquire territory belonging to one of the states, the court ruled in the affirmative.
"I can't imagine that the Justice Department could be anything but more cautious in exercise of its discretion" to prosecute individuals, rather than firms, "in the aftermath of the process that resulted in the prosecution of Arthur Andersen," he said.
It suggests a new treaty clause saying that "courts and tribunals of the member states shall rule on questions of community law which they encounter in exercise of their national jurisdiction".
They concluded: "In our judgment, the clear and necessary implication from these provisions taken separately and cumulatively is that parliament intended EU rights to have effect in domestic law and that this effect should not be capable of being undone or overridden by action taken by the crown in exercise of its prerogative powers".
However, separate insignia for the President of the Senate, in exercise of duties as acting head of state under Article 86, was created in 1986.
Such norms are often violated explicitly in exercises of power for various ends, such as wealth, security, or cultural survival.
We acknowledge the willingness of the team to participate in exercises of this nature.
Soloway believes the President's newly articulated position on DOMA could weigh heavily in the exercise of discretion in cases involving binational same-sex married couples.
Being a man lay not in the exercise of power, but in the equal sharing of it.
The fun is not in beating competitors but in the exercise of increasingly complex managerial capabilities.
