The credibility of a witness may be attacked by any party, including the party calling the witness.
Md. R. Evid. 5-607
This Rule is derived from F.R.Ev. 607 and Rule 1-501.
Committee note: This Rule eliminates the common law "voucher rule. It does not permit a party to call a witness solely as a subterfuge to place an otherwise substantively inadmissible statement before the jury. It is not intended to otherwise affect existing law concerning the court's discretion to control direct and cross-examination.