
980 P.2d 178 (1999)
160 Or. App. 260
Marvin PEEK, Appellant,
v.
S. Frank THOMPSON, Superintendent, Oregon State Penitentiary, Respondent.
(97C-12445; CA A100853)
Court of Appeals of Oregon, En Banc.
Argued and Submitted October 7, 1998.
Resubmitted February 3, 1999.
Decided April 28, 1999.
*179 Jay Edwards, Salem, argued the cause and filed the brief for appellant.
John T. Bagg, Assistant Attorney General, argued the cause for respondent. With him on the brief were Hardy Myers, Attorney General, and Michael D. Reynolds, Solicitor General.
Before DEITS, Chief Judge, and EDMONDS, De MUNIZ, LANDAU, HASELTON, ARMSTRONG, WOLLHEIM and BREWER, Judges, and WARREN, Senior Judge.
ARMSTRONG, J.
Plaintiff[1] appeals a judgment dismissing a writ of habeas corpus. He asserts that the Board of Parole and Post-Prison Supervision (the Board) failed to follow the applicable statute and administrative rules in extending his parole release date for two years. We reverse.
Many of the arguments that plaintiff raises parallel those that we discussed in Weidner v. Armenakis, 154 Or.App. 12, 959 P.2d 623 (1998), withdrawn by order July 17, 1998, *180 reasoning reaffirmed and readopted Merrill v. Johnson, 155 Or.App. 295, 964 P.2d 284, rev. den. 328 Or. 40 (1998),[2] and involve the Board's authority to extend a parole release date under ORS 144.125(3) (1991). That statute requires the existence of a severe emotional disturbance constituting a danger to the health or safety of the community before the Board may extend the release date. In Weidner, we concluded that ORS 144.125(3) (1991) did not require that there be a psychiatric or psychological diagnosis of that condition. Rather, we held that it was the Board's responsibility to decide whether a prisoner had such a condition and that in doing so it could rely on all the evidence in the record; it was not limited to considering only the psychiatric or psychological report.
In this case, plaintiff relies on an administrative rule that we did not consider in Weidner, because it was not cited or argued to us. That rule shows that, at least during the period that the rule was in effect, the Board believed that a psychiatric or psychological diagnosis that met the statutory requirements was essential to the Board's authority to extend the release date. Thus, the broader construction that we gave the statute in Weidner, to which we adhere in this opinion, is not controlling for that period. Because plaintiff committed his offenses when the rule was in effect, it continues to apply to the Board's consideration of his case. The Board, however, followed the approach that we approved in Weidner, with the result that it has not decided whether the psychologist's diagnosis meets the statutory standard. The trial court on remand should give the Board an opportunity to make that decision.
Plaintiff has been imprisoned since early 1989 for offenses that he committed in late 1988. Shortly after his imprisonment, the Board applied the matrix system that was then in effect and set a parole release date of October 30, 1997. On March 7, 1997, a psychologist interviewed plaintiff; the psychologist prepared a report a few days later. On May 7, the Board issued an order extending plaintiff's parole release date to October 30, 1999. It gave the following explanation of its decision:
"The Board, based on all the information it is considering at this hearing finds that the doctor's diagnosis coupled with all the information it is considering, does result in a finding of a present severe emotional disturbance that constitutes a danger to the health or the safety of the community. The Board has considered this matter under the laws in effect at the time of the commitment offense."
(Capitalization altered.)
The first issue is whether the Board could extend plaintiff's release date without first determining that the psychologist had diagnosed plaintiff with a severe emotional disturbance that constitutes a danger to the health or safety of the community. That issue arises under ORS 144.125(3) (1991), which provided at the time of plaintiff's offenses:
"If a psychiatric or psychological diagnosis of present severe emotional disturbance such as to constitute a danger to the health or safety of the community has been made with respect to the prisoner, the board may order the postponement of the scheduled parole release until a specified future date."
In Weidner, we held that the statute referred to a legal, rather than medical, standard; that an express diagnosis that met all of the statutory criteria was therefore not necessary; and that the Board was entitled to use any information before it in determining whether the prisoner's condition satisfied the statutory criteria. 154 Or.App. at 17, 959 P.2d 623. We rejected the dissent's argument that the statute required the Board to determine from the psychiatric or psychological report alone whether there was a diagnosis that gave the Board the authority to extend the release date. 154 Or.App. at 21-22, 959 P.2d 623 (Warren, J., dissenting).
In this case, plaintiff has cited OAR 255-60-006 (1988) in support of the position that we rejected in Weidner, an administrative *181 rule that we did not consider in that case. That rule shows that, at the time of plaintiff's offenses, the Board understood its role in very much the way that the dissent in Weidner suggested. OAR 255-60-006 (1988) covered a number of issues related to a prisoner's release on parole. The relevant portions are subsections (7) and (8):
"(7) The Board may order a psychiatric/psychological report anytime prior to release. If the record indicates that a psychiatric or psychological condition of severe emotional disturbance, such as to constitute a danger to the health or safety of the community, is present, the Board may consider deferring parole release until a specified future date.
"(8) If the evaluation does not make a finding of severe emotional disturbance such as to constitute a danger to the health or safety of the community, the Board shall affirm the parole release date and set parole conditions."
(Emphasis added.) Plaintiff also points out that in 1983 the Board's chair stated that the Board had no basis to refuse to release another prisoner, because all three psychological reports indicated that he was not emotionally disturbed or dangerous. The Board's attorney's legal opinion was that its hands were tied. See O'Bremski v. Maass, 905 F.2d 281, 285 (9th Cir.1990).
The Board has authority to adopt rules applicable to parole. ORS 144.050. OAR 255-60-006(8) was such a rule, and the Board adopted it within its delegated authority. The rule expressly required the Board to affirm a parole release date unless the evaluation made the finding that ORS 144.125(3) contemplates.[3] It is, of course, axiomatic that an agency must follow its own rules. Moore v. OSP, 16 Or.App. 536, 519 P.2d 389 (1974); see also Aetna Casualty & Surety Co. v. Sue A. Blanton, D.C., 139 Or.App. 283, 287, 911 P.2d 363 (1996). Even if an agency is not required to adopt a rule, once it has done so it must follow what it adopted. Harsh Investment Corp. v. State Housing Division, 88 Or.App. 151, 744 P.2d 588 (1987), rev. den. 305 Or. 273, 752 P.2d 1219 (1988). The rule may limit what an agency would otherwise be able to do. "An agency which is vested with discretion by statute may limit its own discretion in its regulations." Wyers v. Dressler, 42 Or.App. 799, 807, 601 P.2d 1268 (1979), rev. den. 288 Or. 527 (1980), overruled on other grounds, Mendieta v. Division of State Lands, 148 Or.App. 586, 941 P.2d 582 (1997), rev. dismissed 328 Or. 331 (1999). Thus, the question is not, as it was in Weidner, what the statute requires; rather, the question is what the rule requires.[4]
As the majority and dissenting opinions in Weidner show, it is possible to read ORS 144.125(3) in more than one way. In OAR 255-60-006(8), the Board gave it a meaning that was closer to that of the Weidner dissent than of the Weidner majority. So long as that rule was in effect, it required *182 the Board to treat the statute as requiring a formal finding in the psychiatric or psychological evaluation as a prerequisite to the Board's authority to extend a prisoner's parole release date. That requirement imposes a greater limit on the Board's authority to extend a release date than does allowing the Board to make its own determination, based on all the evidence in the record, of the prisoner's condition. The rule, thus, is more favorable to a prisoner than is the view of the statute that we adopted in Weidner. Because the rule was in effect at the time of plaintiff's offenses and was more favorable to plaintiff than Weidner held ORS 144.125(3) to be,[5] it would violate the ex post facto provisions to apply ORS 144.125(3), rather than OAR 255-60-006(8), to plaintiff. See Williams v. Board of Parole, 112 Or.App. 108, 112, 828 P.2d 465, rev. dismissed 313 Or. 300, 832 P.2d 456 (1992) (rules made pursuant to delegated authority are subject to ex post facto analysis). Because the Board did not determine whether the psychological report made a finding that satisfied the statutory conditions, it erred in extending plaintiff's parole release date.[6]
We next consider whether the psychologist's report would permit the Board to find that the psychologist diagnosed plaintiff as having a severe emotional disturbance that constitutes a danger to the health or safety of the community.[7] If it would not, under the rule the Board did not have the authority to extend plaintiff's parole release date and the trial court on remand should direct plaintiff's release. If it would, the trial court on remand should direct plaintiff's release unless the Board, under the relevant legal authority including OAR 255-60-006(8) (1988), determines to extend plaintiff's parole release date. See Meadows v. Schiedler, 143 Or.App. 213, 221, 924 P.2d 314 (1996) (similar conditions on remand when Board improperly applied amended statute).
Because of the importance of the psychological report under the rule, we summarize it at some length. The psychologist first noted that plaintiff's last disciplinary citation came in 1990, for having THC in his system. He then summarized plaintiff's description of his offenses, noting that plaintiff admitted the conduct that constituted the crimes but asserted that he acted in self-defense. Plaintiff's affect was appropriate to mildly anxious; there was no evidence of hallucinations, delusions, or other psychotic thought processes. His judgment appeared adequate, although his insight was slightly limited.
The psychologist then described the results of standardized tests, which suggested someone who had "difficulty incorporating the values and standards of society. Such individuals would tend to be rebellious toward authority figures and often in conflict with them." They would be somewhat impulsive, striving for immediate gratification, acting without considering the consequences, with poor judgment and considerable risk-taking. Such people tend to be insensitive toward others, with elements of hostility and aggressiveness in their makeup.
From the testing and his interview, the psychologist concluded that plaintiff had normal needs for closeness but did not anticipate positive interactions with others. "Mr. Peek tends to intermingle feelings with thinking during problem solving and decision making activities." "He tends to modulate or control emotional discharges much less than other people. He would probably call attention to himself because of the intensity with which he expresses feelings." "He has a very negative, angry attitude toward the environment." *183 His capacity for control and tolerance for stress will usually be adequate, but a great deal of stress would have greater impact on his thinking. He tends to misinterpret his perceptions and to act inappropriately, in part because of excessive negativism and anger. The psychologist did not diagnose an Axis I (clinical disorder) condition; on Axis II (personality disorder), the diagnosis was 301.9, Mixed Personality Disorder with Antisocial and Narcissistic Features. The psychologist concluded that "[o]ver the past five years, [plaintiff] seems to have made determined efforts to rehabilitate himself. However, in my clinical judgment, I should still consider him to be a danger to the community." The danger would be lessened if he were to complete violence prevention and intensive substance abuse programs.
Determining whether the psychologist's diagnosis satisfies the standard of the statute and the rule is not a simple task. As we suggested in Weidner, the statute creates a legal, not a medical standard, so applying a medical diagnosis to that legal standard necessarily requires some translation from one system to the other. The legal determination is whether a "prisoner's emotional disorder was (a) present, (b) severe, and (c) one that made the prisoner a `danger to the health and safety of the community.' A `diagnosis' of a mental disorder, standing alone, will not always provide the necessary information * * *." 154 Or.App. at 18, 959 P.2d 623. In his diagnosis, the psychologist relied on the fourth edition of the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders (DSM-IV).[8] As we noted in Weidner, the DSM-IV emphasizes that a clinical diagnosis of a mental disorder is not sufficient to establish that an individual's condition meets a particular legal standard. "`[T]he fact that an individual's presentation meets the criteria for a DSM-IV diagnosis does not carry any necessary implication regarding the individual's degree of control over the behaviors that may be associated with the disorder.'" 154 Or. App. at 19, 959 P.2d 623 (quoting DSM-IV) (emphasis in Weidner). That is, a diagnosis does not in itself necessarily indicate whether the condition is severe or whether it is the condition that creates whatever danger the person presents.
Under DSM-IV, 301.9, Personality Disorder Not Otherwise Specified, is a diagnosis of
"disorders of personality functioning that do not meet criteria for any specific Personality Disorder. An example is the presence of features of more than one specific Personality Disorder that do not meet the full criteria for any one Personality Disorder (`mixed personality'), but that together cause clinically significant distress or impairment in one or more important areas of functioning (e.g., social or occupational)."
The psychologist diagnosed a personality disorder that has both narcissistic and antisocial features. DSM-IV points out that many highly successful individuals display narcissistic personality traits. Only when the traits are inflexible, maladaptive, and persisting and cause significant impairment or distress would they constitute Narcissistic Personality Disorder. DSM-IV at 661. Similarly, it points out that one must distinguish Antisocial Personality Disorder from criminal behavior that is not accompanied by personality features that are characteristic of the disorder. Again, only when the traits are inflexible or otherwise significantly problematic do they constitute a disorder. DSM-IV at 649.
Reading the psychological evaluation as a whole, thus, there appear to be questions whether the diagnosis is of a severe disorder and whether the disorder causes plaintiff to be dangerous. The evaluation could permit the Board to find that the diagnosis satisfies those conditions, but that conclusion is by no means compelled. It is, thus, something that *184 the trial court on remand should permit the Board to consider. We therefore reverse and remand to permit it to give the Board that opportunity.
Reversed and remanded with instructions to direct petitioner's release unless the Board, applying OAR 255-60-006 (1988), determines to extend petitioner's parole release date.
WARREN, S.J., concurring.
I agree with the majority that the Board erred in failing to determine whether the psychological report made a finding of severe emotional disturbance. That requires a remand to the Board to make that determination. The majority's discussion of the contents of the psychological report is unnecessary to our decision to remand and is inappropriate.
DEITS, C.J., dissenting.
In our decision in Weidner v. Armenakis, 154 Or.App. 12, 959 P.2d 623 (1998), withdrawn by order July 13, 1998, reasoning reaffirmed and readopted in Merrill v. Johnson, 155 Or.App. 295, 964 P.2d 284, rev. den. 328 Or. 40 (1998), we concluded, after considering the text and context of ORS 144.125(3) (1991), that it was the intent of the legislature in adopting that statute that the decision as to whether a plaintiff suffers from a severe emotional disturbance such as to present a danger to the health and safety of the community ultimately is a legal determination to be made by the Board. Weidner, 154 Or.App. at 19, 959 P.2d 623. We held that, based on the statutory language, it was apparent that the legislature intended the Board's decision to be based on its own assessment of the psychiatric or psychological diagnosis, as well as other information in the record before the Board. We explained:
"It is apparent from the text and context of ORS 144.125 (1991) that the determination as to whether a prisoner suffers from a severe emotional disturbance such as to constitute a danger to the health and safety of the community is a judgment that the legislature intended the Board to make. Although a psychiatric or psychological diagnosis is a prerequisite to the Board's consideration of whether the statutory criteria have been met, that diagnosis alone does not dictate the result. ORS 144.125(3) (1991) allows the Board to consider both a psychiatric or psychological diagnosis and other pertinent evidence in the record in exercising its judgment as to whether the prisoner's release should be deferred." 154 Or.App. at 19-20, 959 P.2d 623 (emphasis added).
The text and context of the statute have not changed and, presumably, the legislature's intent has not changed. Nonetheless, the majority holds that our reading of the statute must now be changed because the Board adopted a rule that the majority believes demonstrates that, at least at one time, the Board read the statute differently than we did in Weidner. Even if the majority were right that the Board's rule demonstrates that the Board did read the statute differently than we did, I fail to understand why that requires this court to change our legal conclusion as to the meaning of the statute. In any event, as I will explain, the Board's rule does not reflect a different understanding of the statutory requirements on the part of Board.
The majority concludes that the Board has authority to adopt rules applicable to parole and that, once it does so, it must follow its own rules. Consequently, the majority reasons, if the Board decided that it could only defer a prisoner's release if it had before it a psychiatric or psychological report that includes a finding that the prisoner suffers from a severe emotional disturbance such as to constitute a danger to the health and safety of the community, this court is precluded from holding that the statute requires the Board to make this legal determination based on the diagnosis and other information available to it. I do not agree that the Board's adoption of a rule precludes this court from interpreting the statute in a manner that the court believes is legally correct.
Further, I do not think that the above point can be answered by the argument that, in adopting the rule, the Board was simply delegating the authority that it had been given by the legislature. In my view, such a delegation would be inconsistent with the *185 specific legislative direction to the Board to make this determination. As a general rule, "delegated power cannot be delegated." Voth v. Fisher, 241 Or. 590, 595, 407 P.2d 848 (1965).
By stating that an agency may "limit its own discretion in its regulations," the majority essentially concludes that the Board may delegate the responsibility to make parole release decisions to psychologists and psychiatrists 160 Or.App. at 265, 980 P.2d at 181 (quoting Wyers v. Dressler, 42 Or.App. 799, 807, 601 P.2d 1268 (1979), overruled on other grounds by Mendieta v. Division of State Lands, 148 Or.App. 586, 941 P.2d 582 (1997), rev. dismissed 328 Or. 331 (1999)). However, I do not believe that it follows from Wyers, or any other case, that an agency may abdicate its authority and turn its decisionmaking functions over to others. In Hillman v. North. Wasco Co. PUD, 213 Or. 264, 284, 323 P.2d 664 (1958), overruled on other grounds by Maulding v. Clackamas Co., 278 Or. 359, 563 P.2d 731 (1977), the agency in question had discretion to adopt standards set forth in a national electric safety code. It did not, however, have the ability to adopt prospective future versions of the national code "without hearing or further consideration subsequent changes, modifications or alterations in such code[.]" Id. That was because the agency had a "duty to determine after due consideration whether the changes, modifications, or alterations in the [national] code * * * are necessary and proper for the protection of the health and safety of the citizens of this state. The prohibition against delegation of power imposed on the legislature by the constitution applies with equal, if not greater, force to an administrative agency created by the legislature." Id. at 285, 323 P.2d 664. In Hillman, the court declared void the agency order in which it attempted "abdication of [its] legislative power[.]" Id. at 285-86, 323 P.2d 664. Similarly here, the Parole Board may not abdicate its duty to apply the legal standard articulated in the statute and determine whether an inmate suffers from a severe emotional disturbance such as to constitute a danger to the health or safety of the community to psychiatrists and psychologists.
Even if I am mistaken and the Board did have the authority to adopt the rule as the majority reads it, it makes no difference because, as I will discuss, the majority's reading of the rule is wrong. The rule in question, OAR 255-60-006 (1988) provides in part:
"(7) The Board may order a psychiatric/psychological report anytime prior to release. If the record indicates that a psychiatric or psychological condition of severe emotional disturbance, such as to constitute a danger to the health or safety of the community, is present, the Board may consider deferring parole release until a specified future date.
"(8) If the evaluation does not make a finding of severe emotional disturbance such as to constitute a danger to the health or safety of the community, the Board shall affirm the parole release date and set parole conditions." (Emphasis added.)
The majority construes OAR 255-60-006(8) as meaning that the psychiatric/psychological report mentioned in OAR 255-60-006(7) must itself include "a finding of severe emotional disturbance such as to constitute a danger to the health or safety of the community." 160 Or.App. at 264, 980 P.2d at 181. With all due respect, that is not what the language of the rule provides. First, the majority makes the assumption that the terms "report" and "record" in section 7 are synonymous. It seems unlikely, however, that the Board would have used two quite different terms in the same subsection to describe exactly the same thing.
Further, the majority assumes, without any discussion, that the "evaluation" mentioned in section 8 of the rule is the "psychiatric/psychological report" mentioned in section (7). From that assumption, the majority concludes that the "psychiatric/psychological report" mentioned in section (7) must itself include a "finding of severe emotional disturbance such as to constitute a danger to the health and safety of the community" as mentioned in section (8).
In my opinion, the majority's assumption that the "evaluation" referred to in section (8) is the same as the report referred to in section (7) is wrong. It is clear from the text *186 of the rule that the "evaluation" mentioned in section (8) is not a synonym for the "psychiatric/psychological report" mentioned in the first sentence of section (7). To assume that the report referenced in section (7) is synonymous to the evaluation mentioned in section (8) renders the entire second sentence of section (7) meaningless:
"If the record indicates that a psychiatric or psychological condition of severe emotional disturbance, such as to constitute a danger to the health or safety of the community, is present, the Board may consider deferring parole release until a specified future date." (Emphasis added.)
Consistent with Weidner, the above sentence indicates that the determination of whether an inmate suffers from a severe emotional disturbance such as to constitute a danger to the health or safety of the community is a determination to be made by the Board, based on what is in the record. Section (8) of the rule, when viewed in the context of that sentencewhich immediately precedes itrefers to the Board's own evaluation of the record.
For the above reasons, I would hold that the rule, as does the statute, requires the Board itself to evaluate the record to determine if the inmate has a present severe emotional disturbance such as to constitute a danger to the health or safety of the community. We should not construe the rule in a manner that renders part of it meaningless, as the majority does. Rather, in my opinion, we should interpret the rule to give effect to all parts of the rule and we should construe it in a manner consistent with ORS 144.125(3) (1991), as we interpreted it in Weidner.
Finally, even assuming that the majority correctly interprets the rule and that the Board has authority to adopt a rule that abdicates its decisionmaking functions, I question the majority's disposition based on the record in this case. The majority remands to the Board for it to make the "legal determination" as to whether "a prisoner's emotional disorder was (a) present, (b) severe, and (c) one that made the prisoner a `danger to the health and safety of the community.'" However, under the rule, as interpreted by the majority, that is a finding that must be in the report itself. It seems to me that, under the majority's reading of the rule, all that the Board may do on remand is determine if the report includes such a finding. If it does, the Board may defer the prisoner's release. If it does not, the Board must release the prisoner. If, as the majority holds, the determination that an inmate suffers from a severe emotional disturbance such as to constitute a danger to the community may be delegated to a psychologist or psychiatrist, there is no legal determination remaining for the Board to undertake. For all of the above reasons, I respectfully dissent.
EDMONDS, LANDAU, and BREWER, JJ., join in this dissent.
NOTES
[1]  As has become our style in habeas corpus cases, in this opinion we will refer to the party seeking the writ as "plaintiff," although it would be more accurate to describe him as "petitioner."
[2]  Although we withdrew our opinion in Weidner after we learned that the case had become moot, for convenience we will refer to it in this opinion, although technically Merrill is the precedential case.
[3]  The dissent suggests that "the evaluation" in OAR 255-60-006(8) (1988) refers to the Board's evaluation. There is no textual foundation for that conclusion. Nothing else in the rule refers to a Board evaluation. On the other hand, the reference to "the" evaluation follows immediately after a reference to a psychiatric or psychological report and most logically refers to itindeed, there is nothing else in the rule to which "the evaluation" can refer. The use of "the" suggests that the rule refers to a specific evaluation that it has already identified; only the psychiatric or psychological report would qualify. The writer of the rule simply used two different terms to refer to the same thing.
[4]  That is not, as the dissent suggests, an issue of delegation. The Board has not delegated anything. It retains its discretion under ORS 144.125(3) to determine whether to extend the parole release date for a person who satisfies the criteria of the statute and the rule. All that the Board has done is to establish the type of evidence that is necessary to satisfy the statutory standard. The Board, of course, determines whether the evidence meets that standard. In that respect, the rule is similar to the requirement of a writing to prove the existence of certain agreements, see ORS 41.580, or the requirement of evidence corroborating a confession or the testimony of an accomplice. See ORS 136.425; ORS 136.440. It is even closer to the rule that expert testimony is usually necessary to prove negligence in professional malpractice cases. See, e.g., Griffith v. Blatt, 158 Or.App. 204, 211, 973 P.2d 385 (1999); Docken v. Ciba-Geigy, 101 Or.App. 252, 790 P.2d 45, rev. den. 310 Or. 195, 795 P.2d 554 (1990).
[5]  The Board amended these rules effective April 5, 1990. We do not consider the meaning or effect of the amendments.
[6]  Plaintiff also relies on rules of the Corrections Division involving the transfer of inmates to and from the Mental Health Division as establishing the criteria that a Board finding must meet. Those rules are not rules of the Board and are otherwise irrelevant to a decision to release a prisoner on parole. We do not consider them further.
[7]  Because of its failure to recognize the effect of OAR 255-06-060 (1989), the Board did not focus on whether the psychologist's report satisfied the criteria of the rule. Instead, it drew its own conclusions about plaintiff's condition. The dissent would rely on those conclusions to sustain the Board's order. They do not, however, resolve the issue that the rule requires the Board to resolve.
[8]  Plaintiff argues that the diagnosis must be based on DSM-III, a predecessor to DSM-IV, because that was the version that existed when the legislature adopted ORS 144.125(3). However, as we indicated in Weidner, the legislature did not adopt the medical terminology and thought of a particular period but, rather, created a legal standard. Whether a medical diagnosis satisfies that legal standard does not depend on whether the diagnosis uses the terminology that was current when the legislature created the standard.
