Qui prior est tempore potior est jure is a Latin phrase which means 'a person before in time is better in right'. Priority in time is given preference in law. When there are equal equities, the first in order of time must prevail.
The maxim “qui prior est tempore potior est jure” applies only in cases in which the equities are equal. [Neslin v. Wells, 104 U.S. 428, 441 (U.S. 1881)]