Rule 601 - Competency to Testify in General; "Dead Man's Rule"(a) In General. Every person is competent to be a witness unless these rules provide otherwise. The following witnesses are incompetent: (1)Insane Persons. A person who is now insane or was insane at the time of the events about which the person is called to testify.(2)Persons Lacking Sufficient Intellect. A child-or any other person-whom the court examines and finds lacks sufficient intellect to testify concerning the matters in issue.(b) The "Dead Man's Rule."(1)Applicability. The "Dead Man's Rule" applies only in a civil case: (A) by or against a party in the party's capacity as an executor, administrator, or guardian; or(B) by or against a decedent's heirs or legal representatives and based in whole or in part on the decedent's oral statement.(2)General Rule. In cases described in subparagraph (b)(1)(A), a party may not testify against another party about an oral statement by the testator, intestate, or ward. In cases described in subparagraph (b)(1)(B), a party may not testify against another party about an oral statement by the decedent.(3)Exceptions. A party may testify against another party about an oral statement by the testator, intestate, ward, or decedent if: (A) the party's testimony about the statement is corroborated; or(B) the opposing party calls the party to testify at the trial about the statement.(4)Instructions. If a court excludes evidence under paragraph (b)(2), the court must instruct the jury that the law prohibits a party from testifying about an oral statement by the testator, intestate, ward, or decedent unless the oral statement is corroborated or the opposing party calls the party to testify at the trial about the statement.Comment to 2015 Restyling: The text of the "Dead Man's Rule" has been streamlined to clarify its meaning without making any substantive changes. The text of former Rule 601(b) (as well as its statutory predecessor, Vernon's Ann. Civ. St. art. 3716) prohibits only a "party" from testifying about the dead man's statements. Despite this, the last sentence of former Rule 601(b) requires the court to instruct the jury when the rule "prohibits an interested party or witness" from testifying. Because the rule prohibits only a "party" from testifying, restyled Rule 601(b)(4) references only "a party," and not "an interested party or witness." To be sure, courts have indicated that the rule (or its statutory predecessor) may be applicable to a witness who is not nominally a party and inapplicable to a witness who is only nominally a party. See, e.g., Chandler v. Welborn, 156 Tex. 312, 294 S.W.2d 801, 809 (1956); Ragsdale v. Ragsdale, 142 Tex. 476, 179 S.W.2d 291, 295 (1944). But these decisions are based on an interpretation of the meaning of "party." Therefore, limiting the court's instruction under restyled Rule 601(b)(4) to "a party" does not change Texas practice. In addition, restyled Rule 601(b) deletes the sentence in former Rule 601(b) that states "[e]xcept for the foregoing, a witness is not precluded from giving evidence . . . because the witness is a party to the action . . ." This sentence is surplusage. Rule 601(b) is a rule of exclusion. If the testimony falls outside the rule of exclusion, its admissibility will be determined by other applicable rules of evidence.