The 2015 ACT Junior Chess Championship is currently underway, and I doing duty as an assistant arbiter to WIM Emma Guo. The tournament is being run as one big swiss (50 players) with players from 18 years down to 5 years of age. It is a FIDE Rated event so everything is being done exactly by the book (as it would be for any event) and this has lead to some interesting situations already.
Three minutes into the first round there was already an issue with castling, and a double whammy at that. Play A correctly claimed that Player B had both castled into check, and had touched his rook first before doing so. Normally these things happen separately, but in this case, after the 2 minute time bonus was awarded Player B had to move the rook rather than the king.
The second case also involved castling but was stranger (and funnier). One of the top seeds asked me what happens if an illegal move is played, but not noticed/claimed until later in the game. "Show me" was my initial reply and I set of to investigate. It turns that the one of the player had illegally castled early in the game (7.Kxd1 followed by 8.O-O-O with the king ending up on g1!) but only realised they had done something wrong around move 35(!) when the game was almost finished. Rule 7.5a comes into play here, and the game was rewound all the way back to move 8 (and the clocks reset to the time at move 8). Again a 2 minute bonus was given to the opponent but in this case the king had to be moved.
The final case was at first an all to familiar situation in junior/schools chess. Players shook hands to end the game, set up the pieces, and then disagreed about the result. One player thought she had agreed to a draw, but the opponent had reported a win. Normally under those situations I endeavour to restart the game (as well as lecture the players on making sure a result is established before shaking hands), but it turned out the position on the board was in fact checkmate for the winner, rendering the rest of the discussion moot. (NB The shake hand draw/resignation confusion has also occurred in adult tournaments I have directed!)
Apart from that the event has run pretty well, with most games sticking to the rules. The final day is tomorrow (3 rounds), with Fred Litchfield out in front and favourite to win the title.