Helibore: I doubt that is the case. After all, if you make a mistake, and the stones are quickly removed the situation is the same. Furthermore, in any serious competition, players must write down their moves anyway.

No, the reason is that you are not allowed to jump a stone twice. If you make a multiple capture using a queen, if you would remove the stones during the move, it may be that it appears the queen has a free path, instead of being blocked by an already taken stone.

While speaking on this subject, shortly after International and other national checker variants appeared, I asked Fencer to make it on the move confirmation visible which checkers had been taken in this move (for instance, by showing them with a blue border). He answered positively, but it still hasn't happened. :(

With nine close related checkers variants, it may be hard to remember which rules apply to which game. Therefore, I made a cheat sheet, condensing all the rules.

                         +-------------+
                         |   Captures  |
+--------+-------+-------+-------------+--------------------------------------+
| Name   | Size  | Prom. | bw lc lr pp |                                      |
+--------+-------+-------+-------------+--------------------------------------+
| US     |  8x8  | King  | N  N  Pe N  |                                      |
+--------+-------+-------+-------------+--------------------------------------+
| Czech  |  8x8  | Queen | N  N  Pe Y  |                                      |
+--------+-------+-------+-------------+--------------------------------------+
| Inter. | 10x10 | Queen | Y  Y  Cb N  |                                      |
+--------+-------+-------+-------------+--------------------------------------+
| Canada | 12x12 | Queen | Y  Y  Cb N  |                                      |
+--------+-------+-------+-------------+--------------------------------------+
| Brazil |  8x8  | Queen | Y  Y  Cb N  |                                      |
+--------+-------+-------+-------------+--------------------------------------+
| Russia |  8x8  | Queen | Y  N  Pc N  |                                      |
+--------+-------+-------+-------------+--------------------------------------+
| Thai   |  8x8  | Queen | N  N  Pe N  | Queen lands directly after stone.    |
+--------+-------+-------+-------------+--------------------------------------+
| Port.  |  8x8  | Queen | N  Y  Pe N  | Capture most queens.                 |
+--------+-------+-------+-------------+--------------------------------------+
| Italy  |  8x8  | King  | N  Y  Pe Y  | 1) Longest capture preference.       |
|        |       |       |             | 2) Capture with King preference.     |
|        |       |       |             | 3) Capture most Kings preference.    |
|        |       |       |             | 4) Capture first King preference.    |
+--------+-------+-------+-------------+--------------------------------------+

+------------------------------------------------------+
| Captures                                             |
+------------------------------------------------------+
| bw:  Stones capture backwards.                       |
| lc:  Longest capture mandatory.                      |
| lr:  Capturing stone reaches last row:               |
|      Pe:  Promotes, and turn ends.                   |
|      Cb:  Continue capturing backwards, if possible. |
|      Pc:  Promotes, continue capturing if possible.  |
| pp:  Capturing with a promoted piece has preference. |
+------------------------------------------------------+

Salkkuman: There doesn't seem to be an official set of checker rules - like there is for chess. Some rulesets seem to have a '40 move' rule, which says that if one players <em>appears</em> to have an advantage, his opponent can ask for a judgement. If the player having the advantage can't convince the referee that he can make progress in the next 40 moves, the game is a draw.

Personally, I'd say that on BK any non-dice game a result (usually a draw) should be declared if a position repeats itself twice. Games that can have positions that repeat themselves include most (excluding Dark chess) chess and checkers variants, Alquerque, Jarmo, Jungle, Tablut, Tank Battle, Halma, Hasami Shogi, and Espionage (although in Espionage, positions should only be equal if exactly the same pieces are on the same fields, not just pieces of the same rank, because of the opponents not knowing the rank of all the pieces).

This however may not be easily programmed.