I was arrested for a felony in 2003. I answered "NO" on the application (which asks for convictions, and the difference between an arrest and conviction is significant and matters).

At GE interview, arrest record comes up. I disclose. I am asked to provide evidence that the arrest did not result in a conviction. I do so. I am approved.

I subsequently apply for NEXUS. Still answer "NO" to "have you been convicted of a crime" question. I get a call from CBSA, asking about arrest. I disclose. I am asked to provide evidence that I was not convicted. I do so. I am approved.

Please stop telling people to disclose arrests on the application. It asks about convictions. Nobody is going to be rejected for failing to disclose an arrest that does not result in a conviction (but you are going to have to prove that no conviction occurred). Because the fact of the matter is that arrests are not disqualifying events on their face. Unadjudicated arrests and a number of criminal convictions are, in fact, disqualifying events (although the arrests are really temporary as long as no conviction occurs).