What is Negligence Per Se?

Legal Definition
Negligence per se is a doctrine within the law of United States of America whereby an act is considered negligent because it violates a statute (or regulation).
-- Wikipedia
Legal Definition
Conduct, whether of action or omission, which may be declared and treated as negligence without any argument or proof as to the particular surrounding circumstances, either because it is in violation of a statute or valid municipal ordinance, or because it is so palpably opposed to the dictates of common prudence that it can be said without hesitation or doubt that no careful person would have been guilty of it. See Missouri Pac. Ry. Co. v. Lee, 70 Tex. 496. 7 S. W. 857; Central It& B. Co. v. Smith, 78 Ga. 694, 3 S E. 397; Murray v. Missouri Pac. R. Co., 101 Mo. 236, 13 S. W. 817, 20 Am. St. Rep. 601; Moser v. Union Traction Co., 205 Pa. 48l, 55 Atl. 15.
-- Black's Law Dictionary
Legal Definition
Under legal provisions this type of conduct automatically constitutes negligence.