Mentis Imperium

Mentis Imperium - the mind control spell. Dominate the mind of target for 24 hours, impossible to fight off. The target will have no memory of the 24 hours. The caster will have complete control over the target during this time.

Harry wondering if this is even possible, studies the incantation and wand movement. It appears to be the precursor to the Imperio curse but this is not against the law because the spell has fallen out favor by the time that law was written. Once he believes that he has the spell down who does he try the spell out on?