[Latin, Of the same matter; on the same subject.] The phrase used in connection with two laws relating to the same subject matter that must be analyzed with each other.
For example, the federal gift tax provisions supplement the federal estate tax provisions. The two are in pari materia and must be read together because the gift tax provisions were enacted to prevent the avoidance of estate taxes.
pari materianoun in consonance, in harmony, on the same matter, read as one, read in tandem, read with reepect of another, read together
PARI MATERIA. Of the same matter; on the same subject; as, laws pari materia must be construed with reference to each other. Bac. Ab. Stat. I. 3.