Rule 4020 - Use Of Deposition At Trial(a) If all or part of a deposition is offered in evidence as substantive evidence of its contents because of the unavailability of the witness, whether or not a party, the counsel offering said deposition shall first submit to the court such evidence as will enable the court to find that the appropriate facts under Pa. R.Civ.P. 4020(a)(3) exist.(b) An application to the court to use all or part of a deposition of a witness, whether or not a party, as substantive evidence pursuant to Pa. R.Civ.P. 4020(a)(3) shall be made upon reasonable notice to all parties.Amended effective November 2014.