Tire Jockey Services, Inc. v. Dept. of Environmental Protection - Pa. S.Ct. - February 20, 2007
http://www.courts.state.pa.us/OpPosting/Supreme/out/J-30-2005mo.pdf
There is a two-step analysis when reviewing an agency's interpretation of its governing regulations: (1) whether the interpretation is erroneous or inconsistent with the regulations, and 2) whether the regulation is consistent with the statute under which it was promulgated.
When an agency adopts a regulation pursuant to it own legislative rule-making power, as opposed to its interpretive rule-making power, it is valid and binding on courts as a statute, so long as it is a) adopted within the agency's granted power, b) issued pursuant to proper procedure, and c) reasonable.
When a court reviews a regulation issued pursuant to an agency's legislative rule-making power, the court may not substitute its own judgment for that of the agency to demonstrate that the agency has exceeded its administrative authority. It is not enough that the prescribed system may appear to be unwise or burdensome of inferior to another. Lack of wisdom in exercising agency power is not equivalent to abuse. What has been ordered must appear to be so entirely at odds with fundamental principles as to be the expression of a whim rather than an exercise of judgment.
Regarding the reasonableness prong, appellate courts accord deference to agencies and reverse agency determinations only if they were made in bad faith or they constituted a manifest or flagrant abuse of discretion or a purely arbitrary execution of the agency's duties or functions.
