On Jаnuary 19, 1983, petitioner John R. Barnes was convicted of driving under the influence (DUI), careless driving, and operating a vehicle without an- operator’s license. Subsequently, his conviction was affirmed by the Denver Superior Court. We granted certiorari to dеtermine whether the jury was correctly instructed as to the presumptions contained in Colorado’s *871 DUI statute, section 42-4-1202, 17 C.R.S. (1973 & 1982 Supp.). We now reverse.
I.
Petitioner was arrested and charged on July 21, 1982. At his trial in Denver County Court, the results of an intoxilyzer breath test performed by the arresting officer were admitted into evidence. The test showed the petitioner had a blood alcohol level of 0.172 percent shortly after his arrest. Before the case was submitted to the jury, petitioner objected to instructions concerning the presumption that he was under the influence of alcohol arising from proof of the intoxilyzer results. The trial court rejected his arguments, as did the Denver Superior Court on appeal. Petitioner now argues that the instruction concerning the statutory presumption wаs contrary to Colorado’s DUI statute, that it violated his due process rights because it shifted the burden of persuasion to petitioner, and that it constituted an improper comment on his right to remain silent. We agree with petitioner’s first argument, and therefore reverse.
II.
Petitioner’s initial argument concerns the scope of the presumption created by Colorado’s DUI statute, which provides in pertinent part:
(2) In any prosecution for a [DUI] violation ..., the amount of alcohol in the defendant’s blood or breath at the time of the commission of the alleged offense or within a reasonable time thereafter, as shown by chemical analysis of the defendant’s blood or breath, shall give rise to the following presumptions:
(c) If there was at such time 0.10 or more grams of alcohol per one hundred milliliters of blood as shown by chemical analysis of such person’s blood or if there was at such time 0.10 or more grams of alcohol per two hundred ten liters of breath as shown by chemical analysis of such person’s breath, it shall be 'presumed that the defendant was under the influence of alcohol.
(d) The limitations of this subsection (2) shall not be construed as limiting the introduction, reception, or consideration of any other competent evidence bearing upon the question of whether or not the defendаnt was under the influence of intoxicating liquor or whether or not his ability to operate a vehicle was impaired by the consumption of alcohol.
Section 42-4-1202, 17 C.R.S. (1973 & 1982 Supp.) (emphasis added). 1
The trial court’s charge to the jury, Instruction No. 17, substantially tracked the language of this statute. Instructiоn No. 18 went on to provide:
Rebuttable presumptions are guidelines based upon experience or public policy which are established in the law to assist the jury in their deliberations in the absence of other evidence. Rebuttable prеsumptions take the place of evidence unless rebutted by evidence to the contrary. Unless the presumption is rebutted by evidence to the contrary, you must accept the presumption as if it had been factually established by evidence. When other evidence raises а reasonable doubt as to the presumption, then the presumption disappears.
(Emphasis added).
Petitioner argues that Instruction 18 created a mandatory presumption in violation of section 42-4-1202, which, he contends, authorizes only a permissive inferenсe that a defendant was under the influence of alcohol based on the results of a blood or breath test. 2 The prosecution, on *872 the other hand, responds that the statute— because it uses the word “shall” — creates a mandatory rebuttable presumption by its “plain meaning.” We agree with the petitioner.
Initially, we find it difficult to accept the prosecution’s argument that the phrase “shall be presumed” has a “plain meaning” that we can divine from the face of the statute. The term “presumption” is one of the most ambiguous terms in the legal lexicon. Over the years, the term has been used to describe a variety of eviden-tiary devices with different meaning and effects, fostering, in the process, a “welter of loose language and discordant decisions.”
See, e.g., County Court of Ulster County v. Allen,
In criminal cases, the use of presumptions raises serious concerns because these evidentiary devices potentially conflict with the basic principles that a defendant is presumed innocent and the prosecution must prove guilt beyond a reasonable doubt.
Ulster County,
As a result, to avoid implicating these constitutional limitations, presumptions in criminal cases are ordinarily construed to raise only permissive inferences.
See, e.g., People v. Seven Thirty-Five East Colfax, Inc.,
In this vein, courts in other states reviewing presumptions contained in DUI statutes substantially similar to Colorado’s have concluded that the language “shall be presumed” or its equivalent creates only a permissive inference that a defendant was under the influencе of alcohol.
See, e.g., Commonwealth v. Moreira,
We are strengthened in that conclusion by noting that this сonstruction fulfills what we perceive to be the central purposes of the legislature in enacting the statutory presumption. First, a permissive inference permits explicit guidance of juries, based on scientific criteria, in determining whether a particular defendant is under the influence of alcohol to a “substantial” degree “so as to render the defendant incapable of safely operating a vehicle.”
Thompson v. People,
III.
Since we conclude that the statute authorizes only a permissive inference, we must examine whether the instructions given in this case comport with the statute. In our view, Instruction 18 created a mandatory presumption that petitioner was under the influence of alcohol. Instruсtion 18 told the jurors that they “must accept the presumption as if it had been factually established by the evidence” and that they could reject this presumption only if it was “rebutted by evidence to the contrary.” The instruction used the terms “rebutted” or “rebuttаble” four times. Although the instruction did not explicitly impose any burden on the petitioner, it is unlikely that the jury viewed “rebuttal” as a duty of the prosecution.
*874
The prosecution correctly notes, however, that we cannot judge the petitioner’s claim by еxamining Instruction 18 standing in isolation.
See, e.g., McCune v. People,
Wе are not persuaded, however, that these instructions adequately cured the error contained in Instruction 18. While the instructions must be viewed as a whole, we have noted that where “two instructions are in direct conflict ... and one of the instructions is an incorrect and clearly prejudicial statement of law, the fact that the other instruction contains a correct statement of law cannot cure the error.”
People v. Riley,
The judgment is reversed and the case is remanded to the district court with instructions to return the case to the county court for a new trial.
Notes
. Although this statute has been amended sincе this case arose, the sections cited remain the same. See 42-4-1202, 17 C.R.S. (1984). This case does not involve Colorado’s "per se” DUI statute, which forgoes the use of a presumption and makes it a crime to "drive any vehicle in this state when the amount of alcohol in such person’s blood is 0.15 or more grams of alcohol per hundred milliliters of blood or 0.15 or more grams of alcohol per two hundred ten liters of breath at the time of the commission of the alleged offense, as shown by chemical anаlysis of such person’s blood or breath.” See section 42-4-1202(1.5)(a), 17 C.R.S. (1984).
. Under Colorado law, a defendant is considered "under the influence of intoxicating li
*872
quor" if the degree of influence is “substantial so as to render the defendant incapable of safely operating a vehicle."
Thompson v. People,
.
See also Commonwealth v. DiFrancesco,
.
But cf. State
v.
Childress,
. We find unpersuasive the prosecution’s argument that our holding in
People
v.
Duemig,
. Because we find that Instruction 18 violated the statute, we do not address petitioner’s arguments that the instruction unconstitutionally shifted the burden of persuasion and amounted to an improper comment on his right to remain silent. However, if these issues should arise again, we repeat today what we said in
Wells v. People,
