I know it really would be silly, but a) is it within the rules to declare an ODI innings closed and b) if so, has it been done. If it has not been done could anyone think of a scenario where it could be done?

This was a totally random thought of mine, maybe daft, but I leave it to you guys,

I don't see why not after all the captain is in charge of a team.

The idea is not as silly as it sounds, there could be rain in the offing, and a result needed by one side, a declaration could be the only way to have time for a result.

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Ern

This was my instant reaction as well, however if a side declared any D/L calculations would have to assume that they had batted 50 overs therefore unless a captain was confident that they could bowl a side out very quickly I can't see them declaring.

There have been cases in club cricket where captains have declared to stop the opposition gaining league bonus points.

I played in a game where the opposition captain took pity on the young side I was with (there were only 2 of us over 18) and declared after 30 overs having racked up 230 for 2 - he almost regretted it too, we were up with the run rate until a middle order collapse left us 20 short at the end.

It's not within the rules for ODIs. Law 14 (Declaration and forfeiture) does not apply in ODIs, by virtue of ODI Playing Condition 14 (linked here).

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Spike Milligan

that settles the question, thanks for that 'occasional fan'. but i wonder if they might change the rule incase what Ernest suggested may happen, or a team being allowed to declare due to injury...very unlikely though, i doubt they might ever look at this rule...they are too busy looking into using, super subs, and powerplays...