What is Obsta Principiis?

Legal Definition
Lat. Withstand beginnings; resist the first approaches or encroachments. "It is the duty of courts to be watchful for the constitutional rights of the citizen, and against any stealthy encroachments thereon. Their motto should be 'Obsta principiis.'" Bradley, J., Boyd v. U. S., 116 U. S. 635, 6 Sup. Ct. 535, 29 In Ed. 746.
-- Black's Law Dictionary
Legal Definition
To withstand or resist the beginnings. See 116 U. S. 635, 29 L. Ed. 753, 6 Sup. Ct. Rep. 524.
-- Ballentine's Law Dictionary