Absolutely. I could see freegans and fancy lawyers going after restaurant owners for "giving" them inedible trash. Restaurant owners need to go after freegans and police pre-emptively by charging them wth burglary.
Grrr... That should be: "Restaurant owners and police need to go after freegans pre-emptively by charging them wth burglary."
I'd think an attorney could write up a short disclaimer to be placed on the dumpster:
"Any and all food items placed in this receptacle have been deemed unsuitable for human consumption.The proprietors and the waste management company assume no risk for those who disregard this warning."
Might work