Why can't a dropped pawn deliver checkmate in Shogi? In discussion surrounding another recent question, the fact came up that a "dropped" pawn in Shogi isn't allowed to deliver immediate checkmate, whereas any other type of piece can be dropped to deliver checkmate. This has gotten me (not a Shogi player at all) wondering why that distinction is in the rules:


  Is there a particular rationale, perhaps coming from the other rules of Shogi, for singling out pawns as being unable to deliver checkmate via a drop?
I found this on the web:

The rule that a pawn can not give checkmate probably stems from the rule that a piece may not be placed in a position from where it is unable to promote or continue. A pawn may only give checkmate by being placed directly in front of the emperor; a position from where it is unable to move or promote. It can not take the emperor piece as it could with other pieces, and it can not be promoted until it moves again.
In Shogi, violating rules such as &quot;Two pawns can not occupy the same column&quot; or &quot;a piece can not be placed in a position where it is unable to move or promote&quot; results in an immediate loss for the one who violated the rule. Thus, by placing a pawn in this location, the player automatically loses the game by violation of a rule. The checkmate that the player gives doesn't matter because it was obtained through the rule's violation.
In certain Shogi variations, such as yari shogi, a pawn can be used to give checkmate.