When the officials precisely follow the NCAA rules and approved rulings in certain venues, the 10-second backcourt violation becomes a defacto 9-second backcourt violation. But in other venues, this problem does not occur.
The NCAA has not standardized the display truncation specification for the shot clock. Some clock displays (Type 1) reach 20 at 10 seconds after the clock is started, and other displays (Type 2) reach 20 at approximately 9.01 seconds after the clock is started.
Approved Ruling 236 in the 2023-2024 Men's Basketball Case Book specifies that a 10-second backcourt violation has occurred when the shot clock display shows 20. This is the correct rule for Type 1 displays. For Type 2 displays, this is one second too early.
Video evidence of this clock specification problem is easy to find.
In this clip, we see a Type 1 clock in action:
The Type 1 shot clock display ticks down to 0 at the precise moment the clock expires (at around 1:50 in the clip). So, of course, it ticks down to 1 when one 1 second is left and it ticks down to 20 when 20 seconds are left. And, of course, the clock is stated at the 30-second point.
Early in this next clip, we see the type 2 clock in action:
The Type 2 shot clock display ticks down to 4.9 when 4.9 (or, perhaps 4.99) seconds are left. It ticks down to 5 approximately 1 second before that. I infer that the Type 2 clock implements the mathematical floor function such that it ticks to 5 at approximately 5.99 seconds. So, the Type 1 clock display ticks down to 20 at approximately 20.99 seconds. And, of course, the clock is started at the 30-second point. Hence, the display ticks down to 20 approximately 9.01 seconds after it is started.
The second clip shows that the Dean Dome is equipped with a type 2 shot clock. With slightly less than 3:31 left in the second half of the recent 2/26/24 Miami-UNC game, RJ Davis caught an inbounds pass. After a couple of passes in the backcourt, Cadeau took possession in the backcourt. Cadeau passed to Ingram in the front court. But the officials stopped the clock before the shot clock reached 19. Therefore, there could not have been a 10-second backcourt violation at the time the clock was stopped unless the shot clock was started a bit too late. Overall there may have been a 10-second shot clock violation (a possibility arrived at by adding a fraction of a second based on a possible late clock-shot clock start and the fact that the clock was stopped before the ball was touched by Ingram).
One quick fix is to modify Approved Ruling 236 to specify that a shot clock display of 19 (instead of 20) indicates the violation in venues with Type 2 clocks
