It may perhaps be said there are five ways in which to impeach the testimony of a witness: (1) by disproving facts sworn to by him by the testimony of other witnesses; (2) by prior • statements contradictory of his evidence; (3) by evidence of bad character or reputation; (4) by conviction of infamous crime; (5) and by bias or interest.

While evidence of general bad moral character or reputation is allowed in some jurisdictions, in most of the states it is limited to the general reputation of the witness for truth and veracity, at the time he testifies, in the community in which he resides; i. e., what is generally said about him by those with whom he dwells, or with whom he usually associates.

Where it is sought to impeach the witness on the ground of conviction of an infamous crime, in criminal cases, it is usually held that the record of the conviction is the only admissible evidence thereof, while, in civil cases, some courts have held that such fact might be proved by the testimony of any competent witness having knowledge thereof. It would also seem allowable to ask the witness if he has been in prison, without producing the whole record.

It is also a cardinal rule of the law of evidence that the testimony of a witness cannot be impeached by disproving facts immaterial to the issue, nor on collateral and immaterial matters brought out on cross-examination.