Can I be termed for none disclosure on criminal past were employer doesnt state disclosure period

Here is my story I have been working for a company in Neenah, WI for the past 11 months this was a contract to hire position which was to hire in December but the company started a reorganization around that time so my boss had to postpone my hire. A month ago she told me they were bringing me on full time April 30th 2010 and I would meet with HR for my formal offer and such.

I meet with HR three weeks ago in that meeting they gave me my offer letter which we agreed on. The HR representative told me I need to fill out an application even though I had been working there almost 11 months because they needed it for the background check. I asked about the background check and she stated that it would go back 7 years only. The HR rep asked if I could fill out the application by the end of the day so they could get started right away and I did even though I felt it was rushed.

The section on the application for criminal past I put in my DUI just in case it might show up since I couldn’t remember when I got the darn thing other than that I didn’t put anything down since I haven’t been in trouble with anything else in 7 years.

This is the part where it gets sticky yesterday my boss comes and asks if I can join her in the VP of HR's office not good for me I thought. We go to the office and the VP of HR says hey I have some issues we want to discuss with you on your background check and I said ok. He then proceed to layout a background check that covered the last 20 years back to 1991. My first response to him was why does this go back 20 year when I was told it was to go back 7 years. My boss then said to him yes we do usually only do a 7 year background check, he then add yes it was a mistake made by the background checking company but now that I have the 20 year one I have to use it. What that is complete crap how can they just switch this on me. I offered to discuss the thing on the 20 year background check to no avail the HR VP told me that I didn’t disclose these items on my application and my job offer from them was null now and I was being let go from contract because of non disclosure on my application.

This is completely crazy that they can do this. Nowhere in the job offer, application or verbal discussion does it or did they say I had to disclose 20 years back they verbally told me 7 years only. The application doesn't have anything about any disclosure period required and neither does my job offer state anything about that heck it doesn't even mention anything about the offer being contingent on a drug screen and background check which you would think would be standard language.

I feel like I have been screwed I disclosed 7 years of information like I was asked to but yet they pull a 20 year, of course I would be found lacking in my disclosure. I doesn't seem right that they can legally tell me one then and then do another.

So with this whole thing I wondering if they can just get away with this, my guess is they can but this is a $70,000 year position and with bonuses and vacation over $80,000 so I think it’s worth me check my legal options