These consolidated cases concern the procedures in probable cause hearings held pursuant to former RCW 71.09.090(2) (1995),1 hearings that may take place as part of the annual review of prisoners detained under the sexually violent predator statute. Division One of the Court of Appeals certified the cases to this Court pursuant to RCW 2.06.030(d) and RAP 4.4 to harmonize our majority opinions in In re Detention of Petersen, 138 Wn.2d 70, 980 P.2d 1204 (1999) and In re Detention of Turay, 139 Wn.2d 379, 986 P.2d 790 (1999). We accepted certification on November 7, 2000.
For the reasons detailed infra, we reverse and remand both cases. Specifically, we remand Petersen’s case for a new probable cause hearing after providing the opportunity for discovery. We remand Thorell’s case for an evidentiary hearing.
I
Factual and Procedural Background
A. Ronald L. Petersen
After release from prison, the State committed Ronald L. Petersen as a sexually violent predator pursuant to chapter 71.09 RCW (1995). He has been incarcerated at the Special Commitment Center (SCC) since 1995.
As required by RCW 71.09.070, Petersen had an annual review in 1999.2 SCC psychologist Dr. Vincent Gollogly provided an annual report asserting Petersen continued to satisfy the definition of a sexually violent predator. Petersen noted the deposition of Dr. Gollogly for July 2, 1999. The State then moved for a protective order arguing such a deposition “serves no useful purpose and disrupts an important state interest.” Clerk’s Papers (CP) at 51-54. *793After finding Petersen failed to show good cause as a prerequisite to a deposition, the trial court granted the State’s motion, issued a protective order, and quashed the notice of deposition.
On July 30, 1999, the trial court dismissed Petersen’s petition for an evidentiary hearing, concluding there was no probable cause. Petersen appealed to Division One of the Court of Appeals, which certified the case to this Court.
B. Bernard Thorell
Bernard Thorell has been detained as a sexually violent predator at the SCC since 1998. Beginning in January 1999 Thorell underwent corneal transplant surgery and quadruple bypass surgery with complications, resulting in a delay of the annual review process.
On March 5, 1999, Thorell declined to waive his rights to petition for unconditional discharge or conditional release to a less restrictive alternative and requested a hearing and appointment of counsel. A probable cause hearing was set for April 30, 1999.
Thorell’s 1999 annual evaluation concluded in a report by SCC psychologist Dr. Daniel Yanisch that “Thorell suffers from a mental abnormality that renders him more likely than not to commit predatory sexual offenses if he were released to the community.” CP at 258. Dr. Yanisch also recommended Thorell not be considered for a less restrictive placement.
The primary declarant in support of Thorell was Dr. Thomas Gratzer. He opined Thorell’s risk to reoffend was reduced by the substitution of the drug Depo-Lupron for the drug Luvox into Thorell’s treatment regime. Dr. Gratzer took the same position in his declaration as he did at the original commitment hearing regarding Thorell’s use of the drug Luvox. In addition, Dr. Gratzer had Thorell tested by polygraph and plethysmograph. As there was no evidence of arousal in the plethysmograph examination, he determined it was inconclusive. The physiological responses in the polygraph examination indicated Thorell had answered *794truthfully to questions about sexual arousal and whether or not he had manipulated the plethysmograph evaluation. After the State’s reply, Thorell submitted a new declaration from Dr. Gratzer that stated Thorell was unlikely to reoffend if conditionally released to a less restrictive alternative.
In its June 9, 1999 order, the trial court expressed “[t]he burden is on [Thorell] at the Show Cause hearing to produce evidence sufficient to support the finding.” CP at 351. Based on the State’s annual evaluation and Thorell’s contrary evidence, the trial court concluded Thorell “has not met his burden of establishing probable cause to believe that he is not likely to engage in predatory acts of sexual violence if conditionally released to a less restrictive alternative.” CP at 354. Thorell’s motion for a hearing on the issue of conditional release to a less restrictive alternative was denied.
The court agreed to reconsider the June 9, 1999 decision because the trial court overlooked Dr. Gratzer’s April 28, 1999 declaration on behalf of Thorell. On December 20, 1999, the court denied the petition for reconsideration. In its order it did not restate that the burden to establish probable cause rested on Thorell. Instead, it concluded “the state has established the absence of probable cause to believe that Mr. Thorell is safe to be conditionally released.” CP at 348.
Thorell filed a timely notice and motion for discretionary review, which resulted in this certified consolidated case.
II
Issues
The main issues before this Court include:
(1) Who bears the burden of proof at a show cause hearing pursuant to former RCW 71.09.090(2)?
(2) What is the proper standard of proof to be applied?
*795(3) Do prisoners have the right to depose the State’s expert witness to prepare for such hearings?
Ill
Analysis
A. Burden of Proof
Both this Court’s opinions and those of the United States Supreme Court heavily favor placing the burden of proof on the State in former RCW 71.09.090(2) show cause hearings. For example, in Foucha v. Louisiana, 504 U.S. 71, 112 S. Ct. 1780, 118 L. Ed. 2d 437 (1992), the United States Supreme Court reviewed a Louisiana civil commitment statute similar to our statute. Foucha held the State bears the burden of proof in civil commitment proceedings. Foucha, 504 U.S. at 86. Our Court previously held the State bears the burden of proving that a person be civilly committed under our sexually violent predator statute. See In re Pers. Restraint of Young, 122 Wn.2d 1, 37, 857 P.2d 989 (1993).
However, it is now suggested we have issued two contradictory opinions on point: Petersen, 138 Wn.2d 70 and Turay, 139 Wn.2d 379. However, in Petersen, there was no challenge to the constitutional burden of proof at a show cause hearing. Rather Petersen challenged only the validity of the State’s evaluation on grounds of his right to counsel and right to a personal interview. Petersen, 138 Wn.2d at 91-95. Petersen did not argue the trial court erred by impermissibly placing the burden of proof on him at the show cause hearing. Therefore, although Petersen contains language suggesting the burden rests on the prisoner, see 138 Wn.2d at 90, that issue was not then before us.
Turay asked, for the first time, who bears the burden of proof at a former RCW 71.09.090(2) show cause hearing, and the Court clearly answered that the bearer of this burden is the State, not the prisoner.3 The Court first *796recognized the precedent set by Foucha and Young, see Taray, 139 Wn.2d at 423-24, and then unambiguously held:
[B]oth this court and the United States Supreme Court agree that the State must bear the burden of proof in involuntary civil commitment hearings, and, therefore, the trial court was correct in determining that due process requires that the burden of proof remain upon the State in the show cause hearing. We, therefore, reject the State’s contention that it does not have to bear the burden of proof in show cause hearings held pursuant to RCW 71.09.090.
Id. at 424 (emphasis added). The Court likewise concluded “the State must bear the burden of proof in show cause hearings held pursuant to RCW 71.09.090(2).” Turay, 139 Wn.2d at 424. Unlike Petersen, Taray firmly and explicitly holds the burden of proof rests on the State. And that is also our holding today.
B. Standard of Proof
1. The Probable Cause Standard
Former RCW 71.09.090(2) provides in relevant part:
[t]he court shall set a show cause hearing to determine whether facts exist that warrant a hearing .... If the court at the show cause hearing determines that probable cause exists to believe that the person’s mental abnormality or personality disorder has so changed that the person is not likely to engage in predatory acts of sexual violence if conditionally released to a less restrictive alternative or unconditionally discharged, then the court shall set a hearing on the issue.
(Emphasis added.)
Under this statute the inquiry is whether “facts exist” which warrant a hearing on the merits. The standard of proof is “probable cause.”
*797The probable cause standard is familiar to judges as it is used frequently in the Fourth Amendment context. One of the most common examples is the determination of probable cause to issue a search warrant. There the burden is on the State to recite objective facts and circumstances which, if believed, would lead a neutral and detached person to conclude that more probably than not, evidence of a crime will be found if a search takes place. See Aguilar v. Texas, 378 U.S. 108, 84 S. Ct. 1509, 12 L. Ed. 2d 723 (1964); Spinelli v. United States, 393 U.S. 410, 89 S. Ct. 584, 21 L. Ed. 2d 637 (1969).
Another common Fourth Amendment example is the determination of probable cause on a warrantless arrest. One way to determine whether a warrantless arrest is “reasonable” is to consider whether the State’s evidence, if believed, establishes the officer had reasonable grounds to believe a felony had been or was being committed in his presence. See, e.g., State v. Day, 7 Wn. App. 965, 968-69, 503 P.2d 1098 (1972).
Probable cause exists if the proposition to be proven has been prima facie shown. As discussed above, the court determines whether the facts (or absence thereof)—if believed—warrant more proceedings.
It is argued by counsel that certain trial standards, e.g., clear and convincing, beyond a reasonable doubt, or preponderance of the evidence, should apply to these probable cause hearings. However such evidentiary standards are inconsistent with former RCW 71.09.090(2) because they more than simply determine if “facts exist,” they seek to weigh and measure asserted facts against potentially competing ones. See, e.g., Black’s Law Dictionary 1182 (6th ed. 1990) (A “preponderance of the evidence” standard commonly refers to the weighing of evidence presented by both sides, where the fact finder determines whether the party with the burden of proof has provided the greater evidence.). A trial standard of proof has no application to probable cause determinations, only determinations on the merits after a full presentation of all the evidence where *798that evidence can be weighed and disputes can be resolved by the fact finder according to the appropriate standard of proof. Courts do not “weigh evidence” to determine probable cause.
We hold there are two possible statutory ways for a court to determine there is probable cause to proceed to an evidentiary hearing under former RCW 71.09.090(2): (1) by deficiency in the proof submitted by the State, or (2) by sufficiency of proof by the prisoner.
First, probable cause may be found due to a deficiency in the State’s ability to satisfy its burden to present a prima facie case to justify continued incarceration. As acknowledged in the State’s briefing, it must present “prima faci[e] proof that the person continues to meet the criteria for commitment.” See State’s Br. in Resp. to Thorell’s Third Reply at 2-3. Stated more precisely, the State must make out a prima facie case by setting forth evidence that, if believed, shows (1) the prisoner still has a mental abnormality or personality disorder, i.e., the prisoner has not “so changed,” and (2) this mental abnormality or personality disorder will likely cause the prisoner to engage in predatory acts of sexual violence if conditionally released to a less restrictive alternative or unconditionally discharged. See former RCW 71.09.090(2). If the State cannot or does not prove this prima facie case, there is probable cause to believe continued confinement is not warranted and the matter must be set for a full evidentiary hearing.
The second way probable cause may be established is through the prisoner’s proof. Even if the State carries its burden to prove a prima facie case for continued imprisonment, the prisoner may present his own evidence which, if believed, would show (1) the prisoner no longer suffers from a mental abnormality or personality disorder, i.e., the prisoner has “so changed,” or (2) if the prisoner still suffers from a mental abnormality or personality disorder, the mental abnormality or personality disorder would not likely cause the prisoner to engage in predatory acts of sexual violence if conditionally released to a less restrictive *799alternative or unconditionally discharged. See former RCW 71.09.090(2). If the prisoner makes either showing, there is probable cause that continued incarceration is not warranted. Former RCW 71.09.090(2) then mandates the court to set the matter for a full evidentiary hearing.
2. The Standard of Appellate Review of Probable Cause Determinations
A trial court’s legal conclusion of whether evidence meets the probable cause standard is reviewed de novo. Prior case law on the standard of appellate review of such probable cause determinations is admittedly muddled. Compare, e.g., State v. Perrone, 119 Wn.2d 538, 551, 834 P.2d 611 (1992) (applying a de novo standard as determination involves “point of law”); State v. Estorga, 60 Wn. App. 298, 304 n.3, 803 P.2d 813 (1991) (“We review de novo .. . whether probable cause is established.”); State v. White, 44 Wn. App. 215, 218-19, 720 P.2d 873 (1986) (seemingly applying de novo standard) with State v. Cole, 128 Wn.2d 262, 286, 906 P.2d 925 (1995) (applying an abuse of discretion standard); State v. Wilson, 97 Wn. App. 578, 584, 988 P.2d 463 (1999) (same); State v. Rakosky, 79 Wn. App. 229, 240, 901 P.2d 364 (1995) (Sweeney, J., dissenting) (same). A good example of the confusion is State v. Perez, 92 Wn. App. 1, 963 P.2d 881 (1998), where the Court of Appeals attempted to examine a warrant de novo, afford deference to the magistrate’s probable cause determination, and not defer to the magistrate if the facts fail to constitute probable cause. Perez, 92 Wn. App. at 4. However, controlling authority from our Court, as distinguished from the Court of Appeals, favors de novo review.
Until recently federal case law on the standard of appellate review over probable cause determinations also remained blurred. However, the United States Supreme Court clarified the issue in 1996 in Ornelas v. United States, 517 U.S. 690, 695, 116 S. Ct. 1657, 134 L. Ed. 2d 911 (1996). Ornelas distinguished between two types of determinations made at probable cause hearings. On the one hand, a court determines what qualifies as the “historical facts” in the *800case, i.e., the events “leading up to the stop or search.” Id. at 696. This determination should be given “due weight” on appellate review. Id. at 699.
On the other hand, a court also determines whether these historical facts amount to probable cause. Id. at 696. This latter determination is subject to de novo appellate review. Id. at 699. The Court found de novo review of probable cause determinations serves to clarify legal principles, promotes a unitary system of law, and better aids law enforcement. See id. at 696-98. Accordingly, unlike reviewing historical facts, the Court held “determinations of. . . probable cause should be reviewed de novo on appeal.” Id. at 699.
The State fails to distinguish (or cite) Ornelas when it claims the abuse of discretion standard is the clear rule in Washington. Counsel cite abuse of discretion cases pertaining to Aguilar-Spinelli determinations of probable cause that are based on the credibility and reliability of confidential informants or anonymous tips, i.e., “historical facts.” See State’s Resp. at 2-4 (Thorell) (citing Cole, 128 Wn.2d at 286; State v. Murray, 110 Wn.2d 706, 713, 757 P.2d 487 (1988); State v. Cord, 103 Wn.2d 361, 366, 693 P.2d 81 (1985); Wilson, 97 Wn. App. at 584-85; Rakosky, 79 Wn. App. at 240); State’s Resp. at 19-20 (Thorell) (same); State’s Resp. Br. at 11-13 (Petersen) (same).
However in an Aguilar-Spinelli probable cause context the trial court or magistrate necessarily first must find whether the information from these tips is sufficiently competent to qualify as historical fact. See State v. Jackson, 102 Wn.2d 432, 436-43, 688 P.2d 136 (1984). Fact-finding on reliability and credibility is required. Id. On such matters it makes sense for a magistrate or trial judge to be afforded appropriate discretion on review. Id. However, as described later in Ornelas, once the court makes this factual determination, it then must decide the legal issue whether the qualifying information as a whole amounts to probable cause. As to this legal conclusion, de novo appellate review is necessary.
*801Like the United States Supreme Court in Ornelas, we hold probable cause determinations in this consolidated case must be reviewed de novo. The only question is whether the evidence, or lack thereof, suffices to establish probable cause for an evidentiary hearing. The rule articulated in Ornelas controls.
C. Discovery
This Court has previously held the sexually violent predator statute is civil in nature. Young, 122 Wn.2d at 23 (“In sum, we conclude that the sexually violent predator Statute is civil, not criminal, in nature.”). The rules of civil procedure
govern the procedure in the superior court in all suits of a civil nature whether cognizable as cases at law or in equity with the exceptions stated in rule 81.
CR 1. Rule 81 provides in relevant part:
Except where inconsistent with rules or statutes applicable to special proceedings, these rules shall govern all civil proceedings.
Even assuming former RCW 71.09.090(2) probable cause hearings are “special proceedings,” nothing in that statute is inconsistent with the civil discovery rules.
Accordingly, as with preparation for other civil proceedings, to prepare for a show cause hearing held pursuant to former RCW 71.09.090(2) we hold a prisoner is allowed to depose any of the State’s expert witnesses and conduct such discovery as is permitted by the civil rules.
D. Petersen
Petersen was denied his right to depose Dr. Gollogly to prepare for the probable cause hearing. The trial court issued a protective order denying Petersen the opportunity for such a deposition. The order placed the burden on Petersen to show “good cause” to obtain a deposition.
CR 26(c) governs protective orders. Under this rule, however, the party opposing discovery (here, the State) must show “good cause” to prevent or limit the discovery. *802Placing the duty to show good cause on Petersen violated CR 26(c) and erroneously denied Petersen his right to depose the State’s expert.
E. Thorell
In Thorell’s case the trial court clearly erred when, in its 1999 order, it stated the burden of proof at the probable cause hearing rested on Thorell. However, the court corrected this error in its order on reconsideration. There the court made clear it relied on the State’s evidence in finding no probable cause for an evidentiary hearing. It stated “the state has established the absence of probable cause.” CP at 348. Accordingly, on reconsideration the court properly placed the burden of proof on the State.
Nevertheless, even assuming the State met its burden to prove a prima facie case for continued incarceration at Thorell’s show cause hearing, Thorell presented sufficient evidence to establish prima facie probable cause that continued imprisonment was unlawful. Dr. Gratzer first personally evaluated and interviewed Thorell in 1997. See CP at 130-34 (Letter of Oct. 30,1997). He determined then that certain medication would suppress Thorell’s pedophilic urges. See id. Dr. Gratzer again personally evaluated and interviewed Thorell in 1999 after reviewing all of Thorell’s clinical files and medical notes from the SCC since his commitment. See CP at 216 (Decl. of Dr. Gratzer on Apr. 8, 1999). Dr. Gratzer evaluated the effect of Thorell’s participation in the SCC treatment program that included continued pharmacological treatment with the drug Depo-Lupron. See id. at 216-18. This treatment had a positive effect on Thorell, which Dr. Gratzer confirmed with blood tests, polygraph tests, and plethysmograph tests. See id. at 217. These tests showed the Depo-Lupron treatment significantly reduced Thorell’s “mental abnormality.” See id.
Dr. Gratzer’s declarations specifically detailed why he concluded Thorell’s alleged mental abnormality would not likely cause him to engage in predatory acts of sexual violence if conditionally released to a less restrictive alternative. See CP at 294-97 (Decl. of Dr. Gratzer on July 6, *8031999); CP at 172 (Decl. of Dr. Gratzer on Apr. 28, 1999); CP at 216-18 (Decl. of Dr. Gratzer on Apr. 8, 1999). As to what he meant by “appropriate” less restrictive alternative, Dr. Gratzer set forth at length numerous conditions that should be considered and conditions that should be required.4 See CP at 294-97.
The trial court’s ruling against Thorell was based on its claim the declarations of Dr. Gratzer were “very guarded.” See CP at 357 (Order on Recons.). This rings of weighing the evidence, not simply determining if it exists. As discussed above, the standard of proof at the show cause hearing is probable cause. Here, the trial court misapplied the standard. Even assuming the State made out a prima facie case to justify continuing Thorell’s imprisonment, Thorell provided evidence which, if believed, showed Thorell’s mental abnormality would not likely cause him to engage in predatory acts of sexual violence if conditionally released to a less restrictive alternative. Thus, even though the burden of proof does not rest on Thorell, we conclude he has demonstrated probable cause. Accordingly, the trial court erred when it did not order an evidentiary hearing where factual findings could have been made to resolve the competing evidence and/or inferences therefrom.
IV
Conclusion
For the foregoing reasons, we hold at former RCW 71.09.090(2) probable cause hearings the State, and only the State, has the ultimate burden of proof; the standard of proof is probable cause, i.e., prima facie; and prisoners detained under the sexually violent predator statute have a right to prepare for such hearings through discovery as *804permitted by the civil court rules, including deposing any of the State’s expert witnesses in accordance with these rules.
We remand Petersen’s case to the trial court for a new probable cause hearing after he is afforded the benefit of discovery.
We remand Thorell’s case to the trial court for an evidentiary hearing.
Alexander, C.J., and Smith, Johnson, Madsen, and Chambers, JJ., concur.
RCW 71.09.090 was amended in 2001. See Laws of 2001, ch. 286, § 9. This appeal falls under the former statute.
Previous annual reviews of Petersen formed the basis of an opinion by this Court in 1999. See In re Det. of Petersen, 138 Wn.2d 70, 980 P.2d 1204 (1999).
Unlike Petersen, the burden of proof issue was directly presented to this Court in Turay. See Turay, 139 Wn.2d at 384 (“We granted review of... the State’s cross *796appeal... that the State bears the burden of proof at show cause hearings .. ..”); see also id. at 422-23 (placing the subheading “Burden of Proof at the Show Cause Hearing under RCW 71.09.090(2)” under the larger heading “Substantive Issues Raised by the State”); see also id. at 424 (restating the majority's holding on the burden of proof issue in the “Conclusion” section).
The trial court found “[a] 11 of the conditions of release to which Dr. Gratzer refers are in terms of ‘should be considered.’ ” CP at 348 (Order on Recons.). Dr. Gratzer also set forth five conditions he believed “should be required.” See CP at 296-97 (Decl. of Dr. Gratzer on July 6, 1999).