dissenting. Because I feel that the trial court unreasonably restricted the cross-examination of the defendant’s expert witness and that such rulings prej*225udiced the substantial rights of the plaintiff, I must respectfully dissent from today’s decision.
I agree with the majority in its observation that the trial court has broad discretion in determining the scope of cross-examination. Indeed, the Ohio Rules of Evidence mandate such an approach. However, I will not hesitate to find an abuse of that discretion when a trial court precludes effective cross-examination through the imposition of excessive restraints which thwart the truth-seeking process. This also is dictated by the Rules.9
Evid. R. 403(B) sets forth the two recognized circumstances under which a trial court may exclude relevant evidence. To do so, the probative value of the evidence sought to be admitted must be “substantially outweighed by considerations of undue delay, or needless presentation of cumulative evidence.” Neither of these contingencies was present in the case at hand.
First, inquiry into the pecuniary relationship between the defense attorney and his witness for the purpose of impeachment could hardly be viewed as an “undue delay” to any proceeding. Questions relating to the expert’s alleged bias could have been proffered in a matter of minutes.
Second, such a presentation would not have been cumulative. Although the trial court allowed cross-examination into the more general area of the number of times the witness had testified on behalf of defendants during the past year, the trial court refused to allow the unique relationship which existed between the defense attorney and his witness to be explored. It was this specific and continuing relationship upon which plaintiff sought to impeach the witness. Without it, plaintiff did not possess a sufficient evidentiary basis to argue to the jury the legitimate issues of bias and pecuniary interest.
I fail to see, in a case such as this, where negligence has *226been admitted, how the serious curtailment of cross-examination of the major defense witness could result in anything but prejudice to the substantial rights of the plaintiff. In my view, Judge Putman, writing for the majority in the Court of Appeals’ decision, was correct in holding that:
“* * * The nature of the financial relationship between the non-treating medical expert offering opinion evidence and the attorney favored by his opinion is a proper subject of inquiry. It is properly in the scope of the jury function to determine what extent, if any, that relationship bears subconsciously or otherwise upon the opinion of the witness.
“A ruling disallowing that inquiry * * * is clearly an unreasonable curtailment of that right [of cross-examination].”
Accordingly, I would affirm the judgment of the Court of Appeals.
Celebrezze, C. J., concurs in the foregoing dissenting opinion.
See Evid. R. 611 which states in pertinent part:
“(A) The court shall exercise reasonable control over the mode and order of interrogating witnesses and presenting evidence so a¡s to (1) make the interrogation and ■presentation effective for the ascertainment of the truth * * *
“(B) Cross-examination shall be permitted on all relevant matters and matters affecting credibility." (Emphasis added.)
See, also, O’Brien v. Angley (1980), 63 Ohio St. 2d 159.