Overtime or free hours worked?

[lorit1960]

I work for a non profit organization. .recently we lost our on call nurses so regular staff have been working 8 hour days then covering on call for 16 hours through the night. If we get called to see a client we get a pay that is 2 dollars overt our regular pay rate. ..today they started cutting off staff because some got the extra pay which they claim is overtime. We do not have any written policy in regards to this. ..I'm just curious if other nurses go through this. .and is it legal under labor laws??