The league  is governed by Major League Baseball (MLB) - American League rules with certain overrides and penalties.  Here is a link to the web site with the complete major league rules:   MLB Rules

Override to MLB Rules  Version 3.4
The following rules override the MLB Rules where appropriate:

1.  Game will consist of 7 innings.  10u and below 6 innings.
2.  Pitching distance & base length.
                    8u   40' pitching   60' base length
         9u -  10u  46' pitching   65' base length
       11u - 12u  50' pitching  70' base length
       13u - 14u  54' pitching  80' base length
3.  MHSSA High School Slide or Surrender Rule
4.  Malicious contact at any base is forbidden (umpire's discretion)
5.  Mercy Rule  15 runs after 3 innings 10 Runs after 5 innings (home team bats if behind). 
6.  Spikes/Shoes   9u - 12u  rubber or plastic sheated shoes only.
7.  Courtesy runner for pitcher or catcher and they must be a player not in the game.   If all players are in the game then the courtesy runner will be the last out.
8.  Bats - if you can swing it you can use it except 15u and above -3 bat.
9. Player must be on a valid Northwest Suburban League Online Roster.
10. Umpires no less than 2 in number for each game.
11. Umpires must be no less than 5 years older than the oldest player except 18u -    the umpire may be age 21.
12. Umpires must be unrelated to any player or coaching staff member
13. Home teams must report score within 48 hours of completion or report the date that the game was moved to.   If a home or visiting team does not show for the game the opposing team must file a protest (see below).  Written documentation is a must (e-mail or other).
14. Pitcher can not be removed from the game defensively then go back on the mound, if pitcher stays in the game defensively he can go back on the mound.
15. For rain-out purposes  or any  "Act of God" (example - rain-out, tornado etc.)  4 complete innings consititute a complete game.
16. Starters may re-enter the game 1 time.  Substitutes may not re-enter.
17. Game balls: Pro 9  NFHS - Rawlings R-100 can be substituted.
18. 9u-12u All Players Batting:  If both teams agree to all players batting a  "continuous batting line-up"  is in effect.  If a continuous batting line-up is in effect each team must declare it only at the beginning of the game.  You may not switch during the game.  If a player is injured before his turn in the line-up and can no longer bat then that team will not be penalized with an out, but the player can no longer play in the game.  Next batter assumes the position in the line-up.  This is the only situtation where the order of the line-up can change.
19. 9u-12u All Players Substituted:  If both teams agree all defensive players being able to be substituted as many times as needed   "free substitution"  is in effect. Rule 16 no longer applies, but rule 14 is still in effect.   If free substitution is in effect each team must declare it only at the beginning of the game.  You may not switch during the game.  The batting line-up can not change unless an injury occurs (see rule 18).  
20. Batters may be intentionally walked by the opposing team's coach telling the umpire.   They will not have to throw 4 pitches. 
       

Penalties  (All other penalties are as they appear in MLB rules)

Rules 3,4:  Player is out
Rule 6: Player wearing metal spikes (9u-12u) cannot play.
Rules 7,14,16:  Play is stopped. Player must be replaced. 
Rule 8: Play is stopped.  Player must exchange bat.
Rule 9: Would be a forfeit  if the game is protested and player found ineligble.  
Rule 10: Both teams must agree to play with 1 umpire.  If they do not agree then the home team must schedule another game at visitors field at their expense.
Rules 11,12: Game is played.  A protest must be filed with the league director.  Penalty will be a forfeit.
Rule 13: League director discretion.  Could be a forfeit for home team.
Rule 17: Both teams must agree to play with non-approved baseballs.  If they do not agree then the home team must schedule another game at visitors field at their expense.


Protest:   Team must file a protest (via e-mail) to the league director for that age division by 12:00 noon the day after the game is played.  The opposing team has 72 hours to respond to the protest.   If either of these requirements are not met the opposing team will win the protest.  After both requirements are met the director will rule on the protest.