Deuteronomy 17:8
If there arise a matter too hard for thee in judgment, between blood and blood, between plea and plea, and between stroke and stroke, being matters of controversy within thy gates: then shalt thou arise, and get thee up into the place which the Lord thy God shall choose; (Deuteronomy 17:8)
Matters of controversy.
Cases that could not be settled in the lower courts, and therefore would be transferred to the Levitical courts.
Plea and plea.
A reference to civil suits, involving personal property, debts, and matters of personal loss and injury.
Between blood and blood.
 That is, the shedding of blood that resulted in death—was it accidental? premeditated? a willful murder? (see Ex. 21:12-14). The decision in such a case would determine whether or not the accused would be admitted to a city of refuge.
Too hard.
 That is, for the local courts that were to be established in all their cities (ch. 16:18). The Hebrew reads, literally, “too wonderful,” “surpassing,” or “unusual.” The same word appears in 2 Sam. 1:26; Ps. 118:23; Prov. 30:18; Micah 7:15. The reference is to some point of law that was not clear to the local judges.