Geoffrey:
In one case the judge determined that if the marks (including redness) lasted for more than ten minutes it was ABH.
It seems to me that such a decision, and even not seeing consensual adult spanking as a legitimate activity while some of the ones you mentioned clearly show that people consent to far worse trauma, is blatantly an expression of an individual's opinion rather than an administration of any law. In other words, any judge with anti-kink sentiments has leeway to appoint themselves gods and guardians in court.
While there are probably exceptions, I can't think now of any examples of a court case in the USA where clearly consensual adult spanking was regarded as anything other than a quirky, yet accepted, private variation on adult fun.