NCAA RULE 9-3-4
In the 2009-10 edition of the NCAA Football Rulebook, Rule 9 covers "Conduct of Players and Others Subject to the Rules." Section 3 covers "Blocking, Use of Hands or Arms" and Section 4 is directed at defensive players. Section 3, Article 4 of Rule 9 states that a "defensive player may use hands and arms to push, pull, ward off or lift offensive players when attempting to reach the runner." But they may not use hands and arms to tackle, hold or otherwise illegally obstruct an opponent other than a ball carrier. This is, by definition, defensive holding and carries a 10-yard penalty that is awarded to the offense as well as an automatic first down.