I have been researching the legality of my fiance volunteering while she is here on a visa wavier program as we wait for our K1 visa to be approved. I have read some posts in which people say that it is legal to volunteer as long as you are not taking a position that would otherwise be paid or which you intend to be paid for later.
Based on what government guideline or document are people on this site making this claim? We do not want to make a decision about volunteering until we find information on its legality posted on an official government website.
Thanks for your help

Yes you can volunteer as long as you are not taking away a job from somebody that could get paid in this position or you get paid,that would be illigal.

I was here on a VWP last year and volunteerd in a hospital,it was not a problem at all and they said that foreign ppl often do that.
Infact volunteering can be good on the resume later on