Probative evidence that reasonable and prudent individuals commonly accept in the conduct of their affairs may be admitted at a hearing and given probative effect. Incompetent, irrelevant, immaterial, or unduly repetitious evidence may be excluded. Documentary evidence may be submitted by parties before and at the hearings and for such period of time that the hearing officer may designate the record to remain open after the hearing. On a genuine issue in a contested case a party may call witnesses and cross examine opposing witnesses.