I traveled into the U.S on my Irish passport, even though i have an U.S passport because it was out of date and i didn't have time to renew it. I had to get a visa waiver and lie that i had not been to America or hold any other passport. What is the penalty for this is all I want to know, please. I have three days before the deadline to renew my U.S. passport. Really appreciate some helpful information. I am aware it is illegal i simply want to know if anyone knows the penalty. Thanks
While I am not a lawyer of any kind, I don't think what you did is likely to attract much penalty, although the theoretical maximum penalty is quite high. While it is technically lying on an immigration form, you didn't actually gain any benefit from it. The the thing you achieved, entry to the US, was something you were entitled to anyway.
If this is now all in the past, I would let sleeping dogs lie. Never use the ESTA again. If you can cancel it without explaining why that might be a good idea.