The rec.sport.baseball FAQ

From rule 2.00:

An INFIELD FLY is a fair fly ball (not including a line drive or an attempted bunt) which can be caught by an infielder with ordinary effort, when first and second, or first, second and third bases are occupied, before two are out. The pitcher, catcher, and any outfielder who stations himself in the infield on the play shall be considered infielders for the purpose of this rule.

When it seems apparent that a batted ball will be an Infield Fly, the umpire shall immediately declare "Infield Fly" for the benefit of the runners. If the ball is near the baselines, the umpire shall declare "Infield Fly, If Fair".

The ball is alive and runners may advance at the risk of the ball being caught, or retouch and advance after the ball has been touched, the same as on any fly ball. If the hit becomes a foul ball, it is treated the same as any foul.

If a declared Infield Fly is allowed to fall untouched to the ground, and bounces foul before passing first or third base, it is a foul ball. If a declared Infield Fly falls untouched to the ground outside the baseline, and bounces fair before passing first or third base, it is an Infield Fly.

On the infield fly rule the umpire is to rule whether the ball could ordinarily have been handled by an infielder -- not by some arbitrary limitation such as the grass, or the base lines. The umpire must rule also that that a ball is an infield fly, even if handled by an outfielder, if, in the umpire's judgement, the ball could have been as easily handled by an infielder. The infield fly is in no sense to be considered an appeal play. The umpire's judgement must govern, and the decision should be made immediately.

When an infield fly rule is called, runners may advance at their own risk. If on an infield fly rule, the fielder intentionally drops a fair ball, the ball remains in play despite the provisions of rule 6.05(l). The infield fly rule takes precedence.

Also, from rule 6.05:
A batter is out when --

5. An Infield Fly is declared.

12. An infielder intentionally drops a fair fly ball or line drive, with first, first and second, first and third, or first, second and third base occupied before two are out. The ball is dead and runners shall return to their original base or bases.
    APPROVED RULING: In this situation, the batter is not out if the infielder permits the ball to drop untouched to the ground, except when the Infield Fly rule applies.

Also, from rule 7.08
A runner is out when --

6. He is touched by a batted ball in fair territory before the ball has touched or passed an infielder.... EXCEPTION: If a runner is touching his base when touched by an Infield Fly, he is not out, although the batter is out;...if a runner is touched by an Infield Fly when he is not touching his base, both runner and batter are out.

1. the fielder catches the ball, the batter is out and the runner is safe, or
2. the fielder drops the ball, picks it up and throws to second for the force and the runner is out and the batter is safe.

Rule 5.09:

The ball becomes dead and runners advance one base, or return to their bases, without liability to be put out, when --

3. A balk is committed; runners advance (see Penalty, 8.05)

Also, rule 8.05 (the notorious "balk rule"):
If there is a runner, or runners, it is a balk when --

1. The pitcher, while touching his plate, makes any motion naturally associated with his pitch and fails to make such delivery;

   If a lefthanded or righthanded pitcher swings his free foot back past the back edge of the pitcher's rubber, he is required to pitch to the batter except to throw to second base on a pick-off play.

2. The pitcher, while touching his plate, feints a throw to first base and fails to complete the throw;
3. The pitcher, while touching his plate, fails to step directly toward a base before throwing to that base.
4. The pitcher, while touching his plate, throws, or feints a throw to an unoccupied base, except for the purpose of making a play;
5. The pitcher makes an illegal pitch;

   A quick pitch is an illegal pitch. Umpires will judge a quick pitch as one delivered before the batter is reasonably set in the batter's box. With runners on base the penalty is a balk; with no runners on base, it is a ball. The quick pitch is dangerous and should not be permitted.

6. The pitcher delivers the ball to the batter while he is not facing the batter;
7. The pitcher makes any motion naturally associated with his pitch while he is not touching the pitcher's plate;
8. The pitcher unnecessarily delays the game;
9. The pitcher, without having the ball, stands on or astride the pitcher's plate or while off the plate, he feints a pitch;
10. The pitcher, after coming to a legal pitching position, removes one hand from the ball other than in an actual pitch, or in throwing to a base;
11. The pitcher, while touching his plate, intentionally or accidentally drops the ball;
12. The pitcher, while giving an intentional walk, pitches when the catcher is not in the catcher's box;
13. The pitcher delivers the ball from the Set Position without coming to a stop;

APPROVED RULING: In cases where a pitcher balks and throws wild, either to a base or home plate, a runner or runners may advance beyond the base to which he is entitled at his own risk.

APPROVED RULING: A runner who missed the base to which he is entitled and is called out on appeal shall be considered as having advanced one base for the purposes of this rule.

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. However, certain specifics should be borne in mind:

1. Straddling the pitcher's rubber without the ball is to be interpreted as intent do deceive and ruled a balk.
2. With a runner on first base the pitcher may make a complete turn, without hesitating to first, and throw to second. This is not to be interpreted as throwing to an unoccupied base.

• Batting out of turn, under rule 6.07(b):
  When an improper batter becomes a runner or is put out, and the defensive team appeals to the umpire before the first pitch to the next batter of either team, or before any play or attempted play, the umpire shall (1) declare the proper batter out; and (2) nullify any advance or score made because of a ball batted by the improper batter or because of the improper batter's advance to first on a hit, an error, a base on balls, a hit batter or otherwise. NOTE: if a runner advances, while the improper batter is at bat, on a stolen base, balk, wild pitch, or passed ball, such advance is legal.
• Leaving base early on a fly ball, under rule 7.10(a):
  Any runner shall be called out on appeal when after a fly ball is caught, he fails to retouch his original base before he or his original base is tagged.
  "Retouch", in this rule, means to tag up and start from a contact with the base after the ball is caught. A runner is not permitted to take a flying start from a position in back of his base.
• Missing a base, under rule 7.10(b, c, and d):

Any runner shall be called out on appeal when

2. With the ball in play, while advancing or returning to a base, he fails