The board shall ascertain, after a hearing in which all interested persons shall be given reasonable opportunity to be heard, the logical and reasonable milk marketing areas within the Commonwealth, shall describe the territorial extent thereof, shall designate such areas by name or number, and shall ascertain and maintain such prices paid to producers, to dealers and to stores for milk in the respective milk marketing areas as will be most beneficial to the public interest, best protect the milk industry of the Commonwealth and insure a sufficient quantity of pure and wholesome milk to inhabitants of the Commonwealth, having special regard to the health and welfare of children residing therein.

The board shall base all prices upon all conditions affecting the milk industry in each milk marketing area, including the amount necessary to yield a reasonable return to the producer, which return shall not be less than the cost of production and a reasonable profit to the producer, of the quantity of milk necessary to supply the consumer demand for fluid milk plus a reasonable reserve supply as determined by the board, and a reasonable return on aggregate milk sales by milk dealers or handlers and stores selling milk. A reasonable return shall mean not less than a two and one-half percent (2 ½ %) nor more than a three and one-half percent (3 ½ %) rate of return based on net sales of price-controlled products determined in accordance with generally accepted accounting principles. However, where the board determines that the market for Pennsylvania produced milk is threatened it may establish producer prices designed to market the milk. In ascertaining such returns, the board shall utilize available information concerning producers' cost of production and a cross-section representative of producers, dealers and stores in the area and shall consider unit costs of various types of products and of various sizes of containers.

The board shall file at its office, with each order issued, a general statement in writing of the findings of fact in support of, and the reasons for such order.

The board may, upon its own motion or upon application in writing, from time to time, alter, revise or amend an official order defining milk marketing areas or fixing prices to be charged or paid for milk. Before making, revising or amending any order defining milk marketing areas or fixing prices to be charged or paid for milk, the board shall hold a hearing, after giving reasonable opportunity to be heard to interested persons, of whom the board has notice, and, in the case of any order affecting the public, after giving reasonable notice thereof to the public in such newspaper or newspapers as, in the judgment of the board, shall afford sufficient notice and publicity: Provided, however, That after such hearing, there shall be a further hearing or conference before the board on any proposed order, and notice of such further hearing or conference shall be given to the parties represented and heard at the previous hearing. Upon application in writing from a person aggrieved by an order of the board hereunder, filed within fifteen (15) days after the issuance of the order complained of, or upon its own motion, the board may, within twenty (20) days after the effective date of such order, issue an order revising or amending such order without a further hearing, if such revision or amendment is based on the record of the hearing held prior to the issuance of such order.

“Interested persons,” as used in this section, means all persons who may be affected by an order of the board fixing prices, and who have signified to the board in writing their desire to be notified of such hearings concerning a particular milk market area or areas within the Commonwealth. “Reasonable opportunity to be heard” may be afforded by written notice addressed to the last known address of an interested party by mail, postage prepaid, by deposit in a United States post office or any receptacle thereof. Nothing contained in this section shall be construed to limit or modify the provisions of section three hundred eight of this act¹ relating to the posting and publicizing of orders of the board, including orders made under this article² and the force and effect thereof.

At any hearing provided for herein the testimony of an expert statistician present at the hearing and any printed, typewritten, duplicated, mimeographed or other written treatise, report or statistical data by an expert not present as a witness, if and to the extent it is endorsed as reliable to an expert witness present at the hearing, shall be competent evidence on any subject material to fixing any price under this article. However, the testimony, treatise, report or data must result from a study of facts and conditions in the milk marketing area which is the subject of the hearing.

All provisions of all price-fixing orders of the board shall be presumed to be valid, and the burden of proving any invalidity of any provisions thereof shall be upon the person asserting the same. Any determination by the board, or a court to which an appeal has been taken, that the wholesale or retail prices provided are invalid shall not prevent the enforcement of prices to producers, but any determination that prices to producers are unreasonable shall require the redetermination by the board of wholesale and retail prices as well as prices to producers.

Whenever an order of the board fixing prices is remitted to the board with directions to reform the findings or order in accordance with the opinion of the court, and no further appeal is taken by the board, the board shall make such reformation within thirty days from the entry of the order of the court remitting the price-fixing order to the board.