WINDER v. DIFFENDERFFER. 193

true that a party cannot discredit his own witness; (g) and, there-
fore, if it should appear at the hearing, as has been objected by
this defendant John Diffenderffer, that the plaintiffs have, in truth,
taken testimony to discredit any one of their own witnesses, such
testimony must be rejected. But as the examination cannot be
suspended for the purpose of determining the bearing of any testi-
mony, in this respect, or of ascertaining the competency of a wit-
ness, the cross-examination, by the party who then makes the
objection, cannot be deemed, at the hearing, a waiver of it; because *
a party cannot be presumed to have waived any ground of claim,
or defence, which it was not in his power to have insisted upon,
with effect, at an earlier stage of the case, (h) No injury or dis-
advantage to any suitor can arise from this course of proceeding,
since the court cannot, in any respect, found its decree upon incom-
petent or irrelevant testimony; and if it should do so, it would be
deemed error, and the decree might, on appeal, be for that cause
reversed, (i)

I shall, upon the received principles of the English practice, hold
the party or his solicitor strictly responsible for the propriety and
pertinency of the interrogatories propounded by him to the wit-
nesses. And although commissioners should not confine them-
selves strictly to the letter of the interrogatories; but ought so to
take down every thing, that the whole truth may plainly appear;
yet, they should not insert any matter from a witness, not properly
and substantially pertinent to the interrogatory propounded. (j)
Any scandalous, impertinent or irrelevant matter returned under a
commission may be suppressed and taken off the file; and the party
solicitor, or commissioner on being convicted of the irregularity may
be made to pay the costs or otherwise punished; since it is indis-
pensably necessary, that the court should be enabled to vindicate
the regularity and purity of its proceedings, and prevent its records
from being made the depository of any foul or scandalous matter
foreign from the point in controversy, (k)

(g) Fenton v. Hughes, 7 Ves. 200; Purcell v. McNamara, 8 Ves. 326; Wood v.
Hammerton, 9 Ves. 145; Queen v. The State, 5 H. and J. 232; 1 Bro, Civ. Law,
478; said to be otherwise in criminal cases; State v. Norris, 1 Hayw. Rep. 438.—
(h) Moorhouse v. De Passau, 19 Ves. 433; S. C. Coop. 300; Harrison v. Courtauld,
4 Cond. Chan. Rep. 499.—(i) Clarke v. Turton, 11 Ves. 240.—(j) 4 Inst. 278;
Whitelocke v. Baker, 13 Ves. 515.—(k) Sandford v. Remington, 2 Vet. Jan. 189;
Cooth v. Jackson, 6 Ves. 41; Eastham v. Liddell, 12 Yes. 201; Mill v. Mill, 12
Ves. 408; 1 Harr. Pra. Chan. 455.