I guess I should probably know the answer to this, but it has never happened to me before and my search did not provide an answer. I was on an Air Canada flight from YYZ to ORD connecting in ORD onto United. There was a mechanical issue with the AC plane and I missed my connection which was the last one for the evening so I had to overnight in Chicago. AC made me check my bag. I normally carry-on my rollaboard, but AC said it was too big (it meets UA's dimensional requirements). The GA told us we could pick up our baggage in baggage claim. My bag didn't show up and when I asked the AC rep about my bag she told me it was against the law for them to give me my bag because it was checked through to my final destination not ORD. So I had no clean clothes or toiletry kit. Is this true? Is it against the law for them to give me my bag. Thanks.