¶ 86. (concurring in part, dissenting in part). I respectfully dissent in part. I would conclude that Carney-Hayes should be allowed to ask two of the witnesses here, Avery and Verbracken, about their own standards of care, provided Carney-Hayes can qualify them as experts. I would conclude that the answers to these questions are not privileged under Burnett v. Alt, 224 Wis. 2d 72, 589 N.W.2d 21 (1999), and this court's decision just last term in Glenn v. Plante, 2004 WI 24, 269 Wis. 2d 575, 676 N.W.2d 413.
*102¶ 87. Before jumping into the analysis, the following background provides context. Carney-Hayes has filed suit against Northwest Wisconsin Homecare, Inc., and Avery. Carney-Hayes has alleged that on April 7, 1999, Carney-Hayes suffered injury while under the custody, care, supervision, and/or treatment of Avery. Carney-Hayes alleged that her injuries and resulting damages were caused by negligence of Northwest, its agents, servants, ostensible agents, and/or employees, and/or Kathy Avery.
¶ 88. During discovery, the following disputes arose:
Carney-Hayes wants to ask Avery (Carney-Hayes' registered nurse) about her standard of care.
Carney-Hayes wants to ask Verbracken (Carney-Hayes' case manager who wrote Carney-Hayes' plan of care) about her standard of care and about Avery's standard of care.
Finally, Carney-Hayes wants to ask Fontaine (a supervisor responsible for Avery's training) about what a manager's standard of care was regarding orienting a nurse to a new patient and whether Avery acted according to the standard of care.1
*103¶ 89. Turning to Alt, one of the issues in that case was whether an expert witness had a legal privilege to refuse to answer questions posed that required expert opinions. Alt, 224 Wis. 2d at 82. In that case, Cline, an obstetrician, delivered a child, Cody Alt, after performing a cesarean section on the mother, Dawn Alt. Id. at 79-80. Cody sustained serious injuries from the delivery. Id. at 80. The Alts (Cody, Dawn, and the father, Mark), sued Cline for negligence. Id. The Alts named one of Cody's treating physicians, Acosta, as an expert. Id. Acosta provided prenatal care to Dawn and wrote her discharge summary following Cody’s birth, but he was not present at the delivery. Id. During discovery, the Alts asked Acosta a question that called for an expert opinion. Id. at 81, 84. Specifically, the question was, "No matter what the cause, a patient with a history of term pregnancy and a gush of blood[,] that's abnormal?" Id. at 81 (brackets in original). Acosta refused to answer the question.2
¶ 90. This court recognized that as a general rule, no person has a privilege to refuse to give evidence.3 Id. *104at 84. The Alt court also recognized that "[privileges are the exception, not the rule." Id. at 85.
¶ 91. Nevertheless, this court found an implicit expert-privilege in Wis. Stat. § 907.06(1). Alt, 224 Wis. 2d at 86. That section provides that "[t]he judge may appoint any expert witnesses agreed upon by the parties, and may appoint witnesses of the judge's own selection. An expert witness shall not be appointed by the judge unless the expert witness consents to act." Id. (emphasis in original). The Alt court concluded that "this express grant implies a privilege to refuse to testify if the expert is called by a litigant." Id. Because a court cannot compel an expert witness to testify, this court determined that "it logically follows that a litigant should not be able to so compel an expert." Id.
¶ 92. This "unearthed and hitherto unknown privilege permitting expert witnesses to decline to give opinions against their will," 7 Daniel D. Blinka, Wisconsin Practice: Wisconsin Evidence, § 702.7, at 514 (2d ed. 2001), was not limitless, however. Striking a balance "between the right of expert witnesses to be free from testifying against their will and the needs of the court and litigants for testimony," Alt, 224 Wis. 2d at 88, this court outlined the parameters of this newly created broad qualified expert privilege as follows:
[AJbsent a showing of compelling circumstances, an expert cannot be compelled to give expert testimony whether the inquiry asks for the expert's existing opinions or would require further work. In addition to demonstrating a compelling need for the expert's testimony, the party seeking the expert's testimony must present a plan of reasonable compensation. Finally, if the party seeking an expert's opinion is able to show a compelling need for the expert's opinion, an expert can *105only be compelled to give existing opinions. Under no circumstances can an expert be required to do additional preparation.
Id. at 89 (footnote omitted).
¶ 93. Applying this privilege to Acosta, this court concluded that Acosta did not have to answer the question presented because he was no more or less qualified than any other obstetrician to give an expert opinion regarding the question asked. Id. at 90. However, Acosta did have to testify as to his observations regarding Dawn's prenatal care. Id.4
¶ 94. This court revisited Alt last term in Glenn. In that case, Glenn's gynecologist, Plante, performed various surgical procedures to treat abdominal pain.5 Glenn, 269 Wis. 2d 575, ¶ 4. Glenn visited another physician, Koh, after the procedures. Id. Koh told Glenn that the procedures were unnecessary, and Glenn then sued Plante for negligence. Id., ¶¶ 4-5. However, Glenn failed to timely name her expert witnesses, so Glenn named Koh. Id., ¶ 6. Koh objected, stating that he did not want to be part of a malpractice action against a fellow local physician. Id., ¶ 7.
¶ 95. At issue in Glenn was whether there were "compelling circumstances" to justify requiring Koh to give expert opinion testimony regarding the standard of care and treatment provided by another physician. Id., ¶¶ 14, 22. This court concluded that there were not, as *106compelling circumstances are linked to "the uniquely necessary or irreplaceable opinion testimony that the expert could provide." Id., ¶ 30. Koh's testimony on another physician's standard of care was not uniquely necessary since other experts could likely testify as to this issue. Id. However, this court concluded that Koh could be "compelled to testify as to his observations as Glenn's treating physician. Such compulsion is considerably different than forcing a physician to testify as to the standard of care and treatment provided by another physician." Id., ¶ 31.
¶ 96. In sum, both Alt and Glenn involved questions that required the treating physicians to offer opinions about another physician's treatment. This court in Glenn characterized Alt as concluding that "Acosta was not so unique as to be required to answer a deposition question that required his expert opinion about another physician's treatment." Id., ¶ 27 (citing Alt, 224 Wis. 2d at 90). And in Glenn, this court concluded that "a treating physician may still be required to testify regarding his or her observations relating to the care or treatment provided to his or her patient, as such compulsion is considerably different than forcing a physician to testify as to the standard of care and treatment provided by another physician."6 Glenn, 269 Wis. 2d 575, ¶ 28.
*107¶ 97. Outside of these types of questions, I would conclude that the rules of evidence govern the scope of questioning. I begin with the general proposition that, subject to other rules, all relevant evidence is admissible. Wis. Stat. § 904.02.7 If a witness is qualified as an expert under Wis. Stat. § 907.02, that witness can testify to scientific, technical, or other specialized knowledge if it will assist the trier of fact to understand the evidence or determine a fact in issue. In addition, testimony in the form of an opinion or inference that is otherwise admissible is not objectionable because it embraces an ultimate issue to be decided by the trier of fact. Wis. Stat. § 907.04.
¶ 98. I recognize that Alt found an implicit privilege under Wis. Stat. § 907.06. Under that section, an expert witness "shall not be appointed by the judge unless the expert witness consents to act," Wis. Stat. § 907.06(1), and is compensated, Wis. Stat. § 907.06(2). While I may not have reached the same conclusion Alt did based on this particular statute, I accept the holdings of Alt and Glenn under principles of stare decisis. Because privileges are the exception and not the rule, however, see Wis. Stat. § 905.01,1 would not extend this implicit privilege beyond the circumstances of Alt and *108Glenn. Under those cases, an expert witness cannot be compelled to testify as to another's standard of care.
¶ 99. An expansive reading of this privilege undermines many rules of evidence (discussed above) and disregards the parties' right and ability to effectively cross-examine witnesses. As we recently stated, "Cross-examination has been described as the greatest legal engine ever invented for the discovery of truth." State v. Stuart, 2005 WI 47, ¶ 26 n.7, 279 Wis.2d 659, 695 N.W.2d 259 (quoting California v. Green, 399 U.S. 149 (1970) (citation and quotations omitted).8
¶ 100. Consistent with these principles, and beginning with the proposition that evidentiary privileges are to be narrowly construed, see Glenn, 269 Wis. 2d 575, ¶ 20, I would conclude that under Alt and Glenn, Avery and Verbracken do not have a privilege to refuse to answer questions regarding their own standard of care. In contrast to the circumstances presented in Alt and Glenn, we are confronted with persons who are already testifying material fact witnesses, who may also be experts. To the extent that Carney-Hayes wants to ask them about their own standard of care as it relates to the treatment that that particular witness provided to Carney-Hayes, she should be allowed to do so. As the Glenn court suggested, this compulsion "is considerably different than forcing a physician to testify as to the standard of care and treatment provided by another physician." Id., ¶ 28. It is one thing to force an expert to take the stand and render an opinion about what someone else did, it is quite another to ask a fact witness on the stand questions that relate to his or her *109own conduct. I would not extend the Alt privilege beyond that which was identified in Glenn.
¶ 101. That said, before Carney-Hayes can ask the questions, she bears the burden, as the proponent of the evidence, of qualifying each witness to answer the questions. See Wis. Stat. § 907.02. Whether an expert is qualified to offer an opinion is a discretionary determination that rests with the trial court. Simpsen v. Madison Gen. Hosp. Ass'n, 48 Wis. 2d 498, 509, 180 N.W.2d 586 (1970). Although the witnesses here may have various sorts of expertise, "the witnesses] must be qualified for each and every question." 7 Daniel D. Blinka, Wisconsin Practice: Wisconsin Evidence, § 702.4 at 490 (2d ed. 2001).
¶ 102. If Carney-Hayes, qualifies Avery and Ver-bracken to answer the standard of care questions with respect to their own conduct, I would also conclude that the responses to those questions are relevant. An ultimate issue of fact in a negligence case is whether the jury believes that the defendants (one of which includes the home care provider that employed Avery and Ver-bracken) acted according to the standard of care. See Nowatske v. Osterloh, 198 Wis. 2d 419, 433-34, 438-39, 543 N.W.2d 265 (1996); Ceplina v. South Milwaukee Sch. Bd., 73 Wis. 2d 338, 342, 243 N.W.2d 183 (1976). The jury will first have to resolve what the standard of care is. If Avery and Verbracken have opinions on what the standard of care is with respect to their own conduct, and whether their own actions conformed to that standard of care, that is all evidence that cuts to the heart of Carney-Hayes' claims.
¶ 103. Thus, because Alt does not apply to questions posed to already testifying material fact witnesses regarding their own standard of care, I would conclude that Carney-Hayes should be allowed to ask both Avery *110and Verbracken9 about their own standards of care, provided Carney-Hayes can qualify them as experts. Assuming they can be qualified, I would conclude that the witnesses can be compelled to answer as those questions are relevant to an ultimate issue of fact. I would also conclude that neither Verbracken nor Avery could be compelled to answer questions about any other person's standard of care, as these questions fall precisely within the holdings of Alt and Glenn.
¶ 104. Accordingly, I would affirm the decision and order of the trial court in all respects. For the foregoing reasons, I therefore respectfully dissent from that portion of the majority opinion with respect to Verbracken. I concur with the result reached by the majority opinion with respect to Avery and Fontaine.
¶ 105. I am authorized to state that Chief Justice SHIRLEY S. ABRAHAMSON and Justice ANN WALSH BRADLEY join this opinion.
Carney-Hayes has not asked Fontaine any questions requiring expert opinions about her own conduct. To the extent Carney-Hayes wants to ask Fontaine to levy opinions about another's standard of care, I agree that these questions fall under the Burnett v. Alt, 224 Wis. 2d 72,589 N.W.2d 21 (1999), privilege. If Fontaine were asked about her own standard of care, I would conclude that these questions are not privileged under Alt for the same reasoning that applies to Avery and Verbracken. Before the answer to that question would be admissible, however, Carney-Hayes would have to first qualify Fontaine to answer the question and would have to proffer a theory of relevance. Because *103Fontaine has not yet been asked about her own standard of care, it is academic to consider issues surrounding Fontaine at this time.
Dr. Acosta was directed not to answer the question by his attorney. Burnett v. Alt, 224 Wis. 2d 72, 81, 589 N.W.2d 21 (1999).
According to Wis. Stat. § 905.01:
Except as provided by or inherent or implicit in statute or in rules adopted by the supreme court or required by the constitution of the United States or Wisconsin, no person has a privilege to:
(1) Refuse to be a witness; or
(2) Refuse to disclose any matter; or
(3) Refuse to produce any object or writing; or
(4) Prevent another from being a witness or disclosing any matter or producing any object or writing.
This court stated: "Dr. Acosta may be unique with respect to the prenatal care provided to Dawn Alt and he must testify as to his observations in that role." Alt, 224 Wis. 2d at 90.
Those procedures included a laparotomy with a right ovarian cystectomy, a right oophorectomy, and hysterectomy. Glenn v. Plante, 2004 WI 24, ¶ 4, 269 Wis. 2d 575, 676 N.W.2d 413.
It is error for the trial court to limit cross-examination of a medical expert witness upon the sole ground that the questions called for expert opinions. Shurpit v. Brah, 30 Wis. 2d 388, 397, 399, 141 N.W.2d 266 (1966). In Shurpit, this court stated as follows:
While we recognize the trial court has some discretion in the scope and extent of the cross-examination of a witness, we deem it was error to prohibit cross-examination of the expert witnesses, including the defendant, upon the sole ground that it called for an opinion of the witness.
*107We have concluded it was error to restrict the cross-examination of the defendant and his expert witness so as to prohibit their opinions as to the quality of the care and treatment rendered by the defendant to the plaintiff.
Id. at 399-00.
Wisconsin Stat. § 904.02 provides:
All relevant evidence is admissible, except as otherwise provided by the constitutions of the United States and the state of Wisconsin, by statute, by these rules, or by other rules adopted by the supreme court. Evidence which is not relevant is not admissible.
I respectfully disagree with the sentiments expressed in the majority opinion regarding cross-examination. See majority op., ¶ 44.
Alternatively, I would agree with the trial court's conclusion that Verbracken is required to answer questions about the standard of care with respect to the plan of care, its preparation, its maintenance and how it should be followed because she was a caregiver for Carney-Hayes and the person who wrote the plan of care that was followed by Avery.