I-192 Waivers: What factors does the ARO consider?

Since the landmark BIA decision of Matter of Hranka in 1978, I-192 waivers and INA 212(d)(3) waivers have been adjudicated by consideration of three (3) factors:

(1) The risk of harm to society if the applicant is admitted;

(2) The seriousness of the applicant's immigration or criminal law violations; and

(3) The nature of the applicant's reasons for wishing to enter the U.S.

These are the only factors for consideration that have been set forth by law.  However, I have noticed in many recent I-192 [INA 212(d)(3)] waiver decisions that the Admissibility Review Office ("ARO") has indicated that Matter of Hranka requires the weighing of at least the aforementioned three (3) factors.  In addition to these factors, the ARO states that it also considers the following factors:

(1) The nature of the offense;

(2) The circumstances which led to the offense;

(3) How recently the offense occured;

(4) Whether it was an isolated incident, or part of a pattern of misconduct;

(5) Evidence of reformation or rehabilitation.

The ARO does not cite the legal authority providing for the consideration of these factors.  Rather, the ARO states that these factors are considered when determining whether or not to exercise its discretion.

I am interested to see how things will play out at the BIA should a waiver applicant appeal a negative decision based upon the consideration of factors that have not been articulated by the BIA.