YOU'd better SAY "YES"- CONSIDER UR WARNED

if you concealled the fact, the consequence could be:

1. FBI background check reveals that you were arrested before. Since your deliberately concealled the fact in order to procue the immigration benefit. The concealled fact is material in determining your case. YOUR I-485 might be denied for this reason.

2. I only had one case which the applicant was arrested but "Forgot" to tell me about it. As a result, he was denied I-485 though his wife got it.

3. Another case, the applicant who reported a bugluary was also taken to the station along awith all others living in the house for finger printing as the police suspect an insider. During the interview, the DAO asked her whether she was finger printed before. Without realizing that, she said NO. Being told that she answered wrong after the interview, she waited an hour for the DAO to show up at the 245 section and finally got to tell her. I also wrote a letter to teh DAO to explain the situation. Her case was approved.

4. It's your personal choice, but consider ur warned.

5. If I were your lawyer, I would have advised you to answer YES to that question as long as you were arrested before, even exeronarated afterwards.
BECAUSE YOU DON"T KNOW what the DAO has in your file.
Any finger print, is hardly missed by USCIS

6. you are making a decision that could potentially jepordize your own interest. Especially, if this was a decision made by others for you. Does it worth the risk to lie on this fact? consider ur warned.

Consider ur warned.

If you are scheduled for an interview, then answer the question as "YES". interview is the 2nd opportunity given to you to correct the error.
If you did not file the I-485 application or fill out the application by yourself, treat the mistake as others. YOU may have an opportunity to correct it.