If the pitcher starts his delivery, in any way, and stops, the pitcher has violated the rule. With runners on base, call a balk. With no runners on base there is no infraction and no penalty.

If a pitcher swings any part of the free foot past the back edge of the pitcher's plate, the pitcher is required to pitch to the batter, except to throw to second base on a pick-off play. Umpires should bear in mind that the purpose of the balk rule is to prevent the pitcher from deliberately deceiving the base runner. If there is doubt in the umpire's mind, the "intent" of the pitcher should govern.

If the pitcher starts his/her delivery, in any way, and stops, the pitcher has violated the rule. Call a balk or illegal pitch. It does not matter if the stop is unintentional – that is, if the pitcher stumbles, for example.

A pitcher, while touching the pitching plate, may spin (or turn) and fake to second base provided the base is occupied. The pitcher may not, however, feint to first base or to third base unless he first properly disengages from the rubber.

The pitcher must, while touching the pitcher's plate, step directly toward a base before throwing to that base. If a pitcher turns or spins off his free foot without actually stepping, or if he turns his body and throws before stepping, it is a balk.

Be mindful what is meant by "step directly toward base." In fact, "directly" is interpreted as within the wedge that is formed by imaginary lines, one from the pitcher's mound to first base and the other from the pitcher's mound to a point halfway from home to first (see illustration, below). The pitcher may not, on his deliver, step into the "homeward" wedge, and then twist and throw to first.

A pitcher must step directly toward a base before throwing to that base; however, he is not required to throw to that base simply because he stepped in that direction. EXCEPTION: When stepping toward first base (while first base is occupied), the pitcher is required to throw to that base.

It is possible, with runners on first and third, for the pitcher to step toward third and not throw, but rather to merely bluff the runner back to third; but then, seeing the runner on first start for second, turn and step toward and throw to first base. This is legal. However, if, with runners on first and third, the pitcher, while in contact with the rubber, steps toward third and then immediately and in practically the same motion wheels and throws to first base, it is obviously an attempt to deceive the runner at first base, and in such a move it is practically impossible to step directly toward first base before the throw to first base, and such a move shall be called a balk. Of course, if the pitcher steps off the pitcher's plate and then makes such a move, it is not a balk.

The above situation frequently happens in one of two ways: (1) a left-hande pitcher, facing first base, steps toward the plate while throwing to first; and (2) a right-hander, who is facing third base, turns and pivots on the front (left) foot while throwing to first. Both of these moves are balks and should be enforced.

Both the "jump turn" and the "stutter-step" are legal provided it's a quick and fluid motion. If there is any interruption, call a balk.

Throwing to an unoccupied base to make an appeal is acceptable and not a balk.

Example of a move that would be a balk: A runner on first breaks for second. The pitcher, sensing that the runner is stealing second, turns and throws to second base, while the runner has returned back at first. Since there was no play at second, call a balk.

A quick pitch is an illegal pitch when there are no runners on base, and a balk with runners on base. The penalty for a quick pitch with no runners on base is awarding a ball to the batter. With runners on base it's a balk. (See exceptions in "Penalty".)

Not sure what to say about this one. I can't even picture it.

This is a move clearly designed to deceive the runners and must be called. The pitcher should not get onto the pitcher's plate until ready to look in for the sign and then pitch.

With no runners on base you have a rule and a penalty with which to enforce directing that the pitcher not delay. In pro ball, the pitcher is required by Rule 5.07(c) to deliver the ball within 12 seconds. In NCAA, the rule is 20 seconds.

With runners on base there is no time limit, but the umpire can use Rule 6.02(c)(8). See also Rule 6.02(a)(8).

This is a move clearly designed to deceive the runners and must be called a balk. The pitcher should not get onto the pitcher's plate until he has the ball and is ready to look in for the sign and then pitch.

A ball, which slips out of a pitcher's hand and crosses the foul line shall be called a ball; otherwise, it should be called no pitch. With runners on base, this would be a balk.

This action occurs only on intentional base on balls, not on "pitch outs" or other situations. Invoke this rule only in the most extreme cases; that is, where the catcher starts moving before the pitcher even starts his delivery.

Once the pitcher has engaged the rubber, then brings hands together in preparation to deliver the pitch, he cannot separate the hands except to go into the windup, to disengage the rubber, or to step and throw to a base. This is a balk whether from the Windup or the Set position.

From the set position, the pitcher must come to a full and discernable stop before delivering the ball to the batter. A change of direction is not considered a stop.

This infraction ("blowing through the stop") is probably the most common balk among young, inexperienced pitchers.

If the pitch is delivered, it's neither a ball nor a strike UNLESS the pitch is ball four; in this case, award the batter first base and any other runners advance if forced. If they don't all advance as a result of the ball four award, enforce the balk, nullify the walk and bring the batter back up to bat.

A major problem is umpires calling time when a pitcher balks. If the pitcher is in the act of delivering the ball, just yell "balk" and stay down and call the pitch.

If the pitcher balks in throwing to a base, yell "balk" and wait to see what happens on the play. (Rule 8.05 Approved Ruling (1)).