No, there is no such rule, but California has a minimum wage (which is a bit above US federal minimum wage), ...
I wouldn't see that as a useful way to set an adequate level of compensation for board members. As it currently stands, to be on the ICANN board, one either needs to have an employer who is willing to pay for the time spent on board work, or else be independently wealthy enough (or I suppose have a spouse with enough income) to subsidize oneself. If ICANN wants to expand the pool of board members to include people outside those two categories, it either needs to drastically slash the amount of time it asks of board members (not unreasonable, no other non-profit I know asks a fraction of what ICANN does), or else pay them enough to make up for the lost income. For the calibre of people I'd hope to attract, that'd would be something upwards of $50,000/yr. If we guess that half the board would accept pay, that'd be $500,000/yr, not a big number in a $65 million budget. If they want really good board members, they should offer $100K. R's, John