CSI Rules

Ever since Billiards Congress of America (BCA) sold its pool league interests to Mark Griffin at Cue Sports International (CSI) in 2004, there has been regular confusion re: BCA vs. BCAPL rules.

The former are the original rules the Congress created. Today, if you search for these rules, you get a BCA page that refers you to the World Pool Association (because BCA is no longer in the league business). You’re asked to follow the “World Standardized Rules.” The latter are the rules CSI uses in its BCAPL and USAPL pool leagues. CSI made a substantial commitment in creating the most complete and intentional rulebook the amateur game has seen, and that continues to evolve through its applied rulings section, plus current topics like sharking, delayed progress (a subset of slow play), and more.

To resolve any confusion, links to the two sets of rules are below. The latter (CSI Rules) are the ones actively being used by sanctioned BCAPL leagues around the globe.

One more note: you may here the term “Modified BCA rules” used in local tourneys. These further complicate matters for players as they try to sort out BCA vs. BCAPL. Generally, these are followed by in-house events and unsanctioned pool event groups. Because if they were official, then they’d simply follow BCAPL rules. CSI is the only sanctioning body for BCA pool left in the world.

Billiard Congress of America (BCA)
Cue Sports International (BCAPL)

The following was originally featured on AZ Billiards in 2014 as a simple resource to players re: understanding key differences in rules, APA vs. BCAPL. We have since augmented that.

Coaching

BCAPL: There is a higher premium on independent player execution, meaning real-time tactical interruptions from the sidelines from a coach are prohibited in singles competition. In doubles competition, open communication and coaching are permitted between teammates in that rack while it’s their turn at the table, provided the non-shooting partner remains either in or at their assigned chair and/or doesn’t physically approach, touch, or point at the table. Communication should be verbal only. In triples, any teammate can coach, following all other expectations above. Communication must not drag out the game. A general limit of 45 seconds between shots can be tracked and enforced to prevent slow play. The 46th second would trigger a foul to the shooting team.
APA: Designated coach timeouts are allowed per game or match (one or more per game, based on skill level, fewer for higher tiers). Coaches can physically approach the table, look at the layout, and talk through strategy or shot selection with the shooting player.

Calling Shots

BCAPL: Yes, the shooter must call the shot, simply “ball and pocket,” not every aspect of he shot. This is includes all non-obvious shots like kicks, banks, caroms, and others. Obvious shots don’t require a call if the players agree to it.
APA: No, slop counts in 8Ball and 9Ball. APA doesn’t play 10Ball. In 8Ball, the 8 must be denoted with a physical marker on the rail closest to the intended pocket.

Pushing After the Break (9Ball, 10Ball)

BCAPL: Yes, in 9Ball or 10Ball, as long as you tell your opponent you’re doing it. Your opponent has a responsibility to be listening for it. They have a choice whether to shoot from where the cue ball comes to rest or have you shoot the next shot. There is push in 8Ball.
APA: No, there is no push in 9Ball or 8Ball. APA doesn’t play 10Ball.

Pocketing the Money Ball (8, 9, or 10) on the Break, no Cue Ball Scratch

BCAPL: Shooter has the option to spot the 8Ball and accept the position of the cue ball where it currently rests, or re-rack the balls and break again. Racks aren’t won on slop in 8Ball. Pocketing the 9 on the break without scratching in 9Ball (aka “a golden break”) is a win. 9Ball is a slop game. Pocketing the 10 on the break without a scratch in 10Ball is NOT a win. 10Ball is a call-shot game. The pocketed 10 is spotted and the next shot is from where the cue ball rests.
APA: Shooter wins the rack in 8Ball and 9Ball. APA doesn’t play 10Ball.

Pocketing the Money Ball (8, 9, or 10) on the Break, with the Addition of a Cue Ball Scratch

BCAPL: Shooter’s inning ends. Opponent has the option to spot the 8Ball and take ball-in-hand anywhere on the table, or re-rack the balls and break again in 8Ball. In 9Ball or 10Ball, the 9 or 10 is spotted and your opponent has ball in hand.
APA: Shooter loses the rack in 8Ball (this rule applies regardless of whether the 8 was pocketed during the break or at a later point in the rack). In 9Ball, it’s the same outcome as in BCAPL above. APA doesn’t play 10Ball.

Scratching “In-game” on the Money Ball (8, 9, or 10) as in the Closing Shot

BCAPL: If the shooter also pockets the 8, then it’s a loss in 8Ball. If the 8 isn’t pocketed, then it’s simply ball-in-hand for the opposing player. in 9Ball or 10Ball, the money ball is spotted and your opponent has ball-in-hand.
APA: Shooter loses the rack in 8Ball. In 9Ball, it’s the same outcome as in BCAPL above. APA doesn’t play 10Ball.

Pocketing a Ball on the Break

BCAPL: The table remains open, and you can shoot any ball to establish suit in 8Ball. In 9Ball or 10Ball, you must shoot at the lowest object ball available, by number. You can also push on your first shot (see above for push shot expectations).
APA: You have to shoot the suit you made (e.g., pocketed a solid, you must shoot solids) in 8Ball. in 9Ball, you have to shoot the lowest available ball, by number. There is no option for a push shot. APA doesn’t play 10Ball.

Using a Jump Cue

BCAPL: Yes, as long as house rules allow it (and most rooms should for BCA players).
APA: No.

Breaking Legally vs. Illegally

BCAPL: If you don't get four balls to a rail in 8Ball, then it's an illegal break. Incoming player re-racks the balls and takes the break, or allows the original breaker to try again. We encourage the former, so there is a penalty and leaning experience for the fouling breaker. In 9Ball or 10Ball, it’s a foul on the breaker, your opponent takes ball-in-hand, and there is no option to re-rack. Three-foul rule is in effect. The breaker is “on one,” meaning one of the three fouls allowed before it’s loss of game has been enabled.
APA: If a ball isn’t pocketed and four balls (not counting the cue ball) don't touch a rail in 8Ball or 9Ball, then it’s a re-rack. Repeat until there's a legal break or the breaker fouls, at which time the other player breaks. No limit on the number of re-racks and breaks. APA doesn’t play 10Ball.

Scratching on the Break

BCAPL: Ball in hand, anywhere on the table.
APA: Opponent must shoot from “the kitchen” (the area behind the break line) in 8Ball. In 9Ball, it’s the same as BCAPL (ball-in-hand). APA doesn’t play 10Ball.

Knocking an Object Ball off the Table

BCAPL: It’s a foul and doesn't get spotted (unless it's the 9Ball or 10Ball in those rotation games). 8Ball off the table is a loss in 8Ball.
APA: It isn’t a foul unless the shooter fouled in some other fashion. The ball would be immediately spotted unless the shooter also pocketed one of their object balls at the same time. In that case, the ball is NOT spotted until they miss, or if the ball knocked off the table is their suit, until they have shot all of their other object balls. It’s then spotted and they continue their turn at the table.

Accidentally Moving a Single Object Ball (Hand or Stick)

BCAPL: Your opponent has the option to leave it in its current position or return it to its previous position. Restoration is the spirit, as it was an accident (vs. punishing the player for it). The shooter shouldn’t grab for the disturbed object ball. Moving it back without communication with your opponent is a foul.
APA: Object ball must be moved back by your opponent to the original position. The ball may remain in its current position only if the moved ball contacts the cue ball, which is a ball-in-hand foul.

Touching an Object Ball, with an Effect on the Outcome of the Shot

BCA: It isn’t a foul if you accidentally touch or disturb a single stationary object ball with any part of your body, clothing or equipment —unless the disturbed ball has an effect on the outcome of the shot.
APA: It isn’t a foul. However, if you accidentally move any other balls during your turn at the table (including the 8Ball), and it in turn comes in contact with the cue ball, then it’s a foul.

"Effect on the outcome of the shot" means that either the disturbed ball makes contact with any ball set in motion as a result of the shot, or that the base of any ball set in motion as a result of the shot passes through the area originally occupied by the disturbed ball. That area is defined as a circle approximately seven inches in diameter centered on the position originally occupied by the disturbed ball.

It is also a foul if you disturb additional balls in BCAPL: 1) if you disturb the cue ball; 2) if you disturb more than one object ball; 3) if a disturbed ball contacts any other ball; 4) if you disturb a ball that is in motion; 5) If the game-winning ball is disturbed in conjunction with a violation of (1) through (4) and falls into a pocket, then it’s loss of game.

Calling “Safe” on a Pocketed Ball

BCA: Yes, and your opponent must shoot next in 8Ball, from where the cue ball comes to rest. There is no calling “safe” in 9Ball or 10Ball.
APA: No.

Practicing During the Match

BCA: No, it’s a foul if you practice at any time during your match, including during timeouts and periods of suspended play. Practice doesn’t have to be moving balls on a table. It can be an air stroke over a table.
APA: Yes.

Placing a Marker on the Table

BCAPL: No object can be placed on the table to mark, guide the shooter, or otherwise denote a shot. It is a foul. The shooter should verbally and/or visually point to all called pockets in 8Ball or 10Ball. 9Ball is a slop game (no call is necessary).
APA: You cannot place chalk or any physical marker on the felt surface to help judge a gap or execute a shot. However, you are encouraged to “mark your pocket” in 8Ball to denote where the 8 is going. Because 8Ball and 9Ball are slop games in APA, no other shots require marking. APA doesn’t play 10Ball. Placing a piece of chalk on the hard wood or laminate surface of the rail (not touching the felt) as a general reference is technically permitted, though discouraged. During an official coach timeout, a coach or player may use equipment like chalk on the rail or point things out, but leaving a physical marker down to gauge an ongoing stance/shot is illegal.

Judging Whether the Cue Ball or an Object Ball Can Fit Through a Gap

BCAPL: Shooter may only use only vision to judge whether the cue ball or an object ball would fit through a gap, or to judge what ball the cue ball would contact first. You may not use any ball, cue, rack, or any other equipment or other part of your body as a width-measuring device.
APA: The shooter may measure the distance with a part of body or equipment. Shooter can also remove a dropped ball and check if ball fits in gap, but it must be removed from the table before shooting.

Here’s an additional Reddit thread on the topic, if you’d like to see other takes on these rules differences.

VNEA and BCAPL have practically identical rules.

TAP rules mostly mirror BCAPL rules, but with the following exceptions:

8 Pocketed on Break, with no Cue Ball Scratch

BCAPL: Shooter has the option to spot the 8Ball and accept the position of the cue ball where it currently rests, or re-rack the balls and break.
TAP: Shooter wins the rack.

8 Pocketed on Break with the Addition of a Cue Ball Scratch

BCAPL: Shooter’s inning ends. Opponent has the option to spot the 8Ball and take ball in hand anywhere on the table, or re-rack the balls and break.
TAP: Shooter loses the rack (this rule applies regardless of whether the 8-ball was pocketed during the break or at a later point in the rack). 

“In-game” Cue Ball Scratch on the 8 (the closing shot, after the break)

BCAPL: If the shooter also pockets the 8, then it’s a loss. If the 8 isn’t pocketed, then it’s simply ball in hand for the opposing player.
TAP: Shooter loses the rack.