We went to the states in 1998 and used the VWE as we had not had any problems with the authorities, since then my partner has been given an HN1 notification (Harassment notification) she was arrested but no charges were brought.
On applying for a job where a CRB check was needed this showed up, should she apply for a visa or is it only judicial convictions that are require to be declared.
If you go under the VWP the US authorities will not know about it unless you tell them.
Whether you should actually get a visa under US law I'm not sure. Arrests need declaring just as much as convictions, but the requirement is in relation to:
crimes of moral turpitude or involving drugs
crimes liable to 5 years or more imprisonment