1920: Substitutions
Initially, players were not allowed to re-enter the game. The rule was changed in 1920 to allow a player to re-enter the game one time. In 1933, the rule was expanded to allow players to re-enter the game twice, and, in 1944 the rule was finally changed to permit players to return to the game an unlimited number of times.
1921: Fouls
In 1921, traveling or running with the ball was changed to a violation and no longer considered a foul.
1923: Free Throws
In 1923, the free throw rule was amended which required the player who was fouled to shoot the free throws.
1932: Midcourt Line
The midcourt line was established in 1932 to eliminate stalling and a rule requiring a team to advance the ball past the midcourt line in less than 10 seconds was enacted, too.
1935: Three Second Area
In 1935 the three second area was created to prevent the offensive players from camping around the basket.
1937: Center Jump
Until
1937 a center jump followed each successful basket. (Note: Making things a bit more complicated, all of these rules were introduced at different times in different leagues. In Europe, the center jump after each score was eliminated after the FIBA Congress in 1936, so there were no center jumps after every basket at the 1936 Berlin Olympic Games. In U.S. college ball it appears to have been eliminated for the 1937-38 season. In the NBL, at first, the home team had the option of whether or not it would be used. It varied upon the team and even the game. In the ABL it was eliminated for the second half of the 1937-38 season.)
1944: Goaltending
In 1944 the goaltending rule was adopted making it illegal for a defensive player to touch the ball on its downward flight. This was in reaction to Bob Kurland (the first regular dunker) and George Mikan standing in front of the basket and swatting practically every opponent shot attempt.
1944: Fouls II
In 1944, player fouls for disqualification were increased from four to five. In the BAA the fouls were increased from five to six in 1948.
1946: Length of Game
BAA games were 48 minutes long (instead of a 40-minute game).
1947: Zone Defenses
Zone
defenses were outlawed in the BAA (in January 1947).
