Britt Colleen Burton appeals from the district court’s decision affirming the administrative suspension of her driver’s license after a breath test disclosed that she had been driving with a breath alcohol content exceeding the legal limit. Burton argues on appeal that the stop of her vehicle (which led to the breath test) was unlawful because the traffic statute that she was deemed to have violated, Idaho Code § 49-808(1), is void for vagueness as applied to her. We hold that the statute is unconstitutionally vague as applied to Burton, and we therefore reverse the decision of the district court.
I.
BACKGROUND
On August 26, 2007, Burton was driving on a two-way, predominantly two-lane, highway when her lane of travel expanded to include a left-hand lane to be used only for passing. Burton stayed in the right-hand lane, never entering the passing lane. According to Burton’s subsequent testimony, as the double-lane configuration was about to end, she saw a traffic sign indicating “that the lanes merged.” She did not signal a turn or lane change as she approached the end of the double-lane expanse. Burton was subsequently stopped by a patrol officer for failure to signal before moving “right or left upon [the] highway” in violation of Idaho Code § 49-808(1). While speaking with Burton, the officer became suspicious that she was intoxicated, and he asked her to submit to a breath test. Burton gave breath samples indicating a blood alcohol content in excess of the legal limit, I.C. § 18-8004. Pursuant to I.C. § 18-8002A, the Idaho Transportation Department administratively suspended Burton’s license due to her failure of the breath test. Burton requested an administrative hearing to contest the suspension as authorized by I.C. § 18-8002A(7). Burton argued, among other things, that her license suspension must be vacated under I.C. § 18-8002A(7)(a) because the officer lacked legal cause to stop her vehicle. No legal cause existed, she argued, because I.C. § 49-808(1) is unconstitutionally vague as applied to the facts of her case. The administrative hearing officer concluded that he had no authority to resolve this constitutional issue and upheld the suspension. Burton appealed to the district court, making the same constitutional challenge to Section 49-808(1). The district court held that the statute is not unconstitutional as applied to Burton and therefore affirmed the hearing officer’s decision.
Burton appeals from the district court’s order. She argues that I.C. § 49-808(1) is void for vagueness as applied to her in this instance because it does not give fair notice that a turn signal is required when two lanes *748merge and does not establish minimal guidelines for uniformity in enforcement.
II.
DISCUSSION
The Idaho Administrative Procedures Act (IDAPA) governs the review of administrative decisions to deny, cancel, suspend, disqualify, revoke or restrict a person’s driver’s license. See I.C. §§ 49-330, 67-5270. In an appeal from the decision of the district court acting in its appellate capacity under IDAPA, this Court reviews the agency record independently of the district court’s decision. Marshall v. Idaho Dep’t of Transp., 137 Idaho 337, 340, 48 P.3d 666, 669 (Ct.App.2002). This Court does not substitute its judgment for that of the agency as to the weight of the evidence presented. I.C. § 67-5279(1); Marshall, 137 Idaho at 340, 48 P.3d at 669. Instead we defer to the agency’s findings of fact unless they are clearly erroneous. Castaneda v. Brighton Corp., 130 Idaho 923, 926, 950 P.2d 1262, 1265 (1998); Marshall 137 Idaho at 340, 48 P.3d at 669. A court may overturn an agency’s decision, however, where its findings, inferences, conclusions or decisions: (a) violate statutory or constitutional provisions; (b) exceed the agency’s statutory authority; (c) are made upon unlawful procedure; (d) are not supported by substantial evidence in the record; or (e) are arbitrary, capricious or an abuse of discretion. I.C. § 67-5279(3). The party challenging the agency decision must demonstrate that the agency erred in a manner specified in I.C. § 67-5279(3) and that a substantial right of that party has been prejudiced. Price v. Payette County Bd. of County Comm’rs, 131 Idaho 426, 429, 958 P.2d 583, 586 (1998); Marshall, 137 Idaho at 340, 48 P.3d at 669. If the agency’s decision is not affirmed on appeal, “it shall be set aside ... and remanded for further proceedings as necessary.” I.C. § 67-5279(3).
Due process requires that all “be informed as to what the State commands or forbids” and that “men of common intelligence” not be forced to guess at the meaning of the criminal law. Smith v. Goguen, 415 U.S. 566, 574, 94 S.Ct. 1242,1248, 39 L.Ed.2d 605, 612 (1974); State v. Cobb, 132 Idaho 195, 197, 969 P.2d 244, 246 (1998). Accordingly, the void-for-vagueness doctrine, premised upon the Due Process Clause of the Fourteenth Amendment, requires that a statute defining criminal conduct or imposing civil sanctions1 be worded with sufficient clarity and definiteness that ordinary people can understand what conduct is prohibited, and the statute must be worded in a manner that does not allow arbitrary and discriminatory enforcement. Village of Hoffman Estates v. Flipside, Hoffman Estates, Inc., 455 U.S. 489, 497-99, 102 S.Ct. 1186, 1192-94, 71 L.Ed.2d 362, 370-72 (1982); State v. Korsen, 138 Idaho 706, 711, 69 P.3d 126, 131 (2003); State v. Martin, 148 Idaho 31, 34, 218 P.3d 10, 13 (Ct.App.2009). Thus, a statute may be void for vagueness if it fails to give adequate notice to people of ordinary intelligence concerning the conduct it proscribes or if it fails to establish minimal guidelines to govern law enforcement or others who must enforce the statute. Korsen, 138 Idaho at 712, 69 P.3d at 132; Martin, 148 Idaho at 35, 218 P.3d at 14.
A statute may be challenged as unconstitutionally vague on its face or as applied to a complainant’s conduct. Id. Here, Burton does not make a facial challenge but contends only that the statute is impermissibly vague as applied to her. To succeed on an “as applied” vagueness challenge, a complainant must show that the statute failed to provide fair notice that the complainant’s specific conduct was prohibited or failed to provide sufficient guidelines such that police had unbridled discretion in determining whether to charge the complainant. Martin, 148 Idaho at 35, 218 P.3d at 14.
The statute that is challenged here, I.C. § 49-808(1), states: “No person shall turn a vehicle onto a highway or move a vehicle right or left upon a highway or merge onto or exit from a highway unless and until *749the movement can be made with reasonable safety nor without giving an appropriate signal.” Burton contends that this statute is vague as applied to her because it does not provide fair notice that a signal is required before one drives into a single lane that stems from the merger of two lanes. The statute does not give notice, she argues, that such a continued forward movement constitutes “moving” a vehicle “right or left upon a highway.”
This Court addressed a related but distinct issue in State v. Dewbre, 133 Idaho 663, 991 P.2d 388 (Ct.App.1999). The driver there contended that the signal requirement defined in Section 49-808 did not apply where a two-lane portion of a highway ended and two traffic signs as well as painted arrows on the highway advised motorists that the right lane was ending and traffic should merge left. The Dewbre case generated a separate opinion from each of the three Court of Appeals judges. The lead opinion stated that the signal requirement applied in that circumstance. A second judge concurred in that result but did not join in the lead opinion’s reasoning, and the third judge dissented. The Dewbre opinion does not have precedential value bearing upon the present case for several reasons. First, the Court in Dewbre was not called upon to address the constitutional issue presented here. Second, there was no opinion that commanded a majority, and third, Dewbre is factually distinguishable because in Dewbre, road signs and arrows on the roadway informed motorists that the right-hand lane was ending and that traffic must merge into the surviving, left-hand lane. In the present case, there is no evidence of such signage or other indicator that one lane was ending and the other surviving.
The officer’s description of the event is cryptic. His affidavit states only that he stopped Burton’s vehicle after he observed it “fail to signal when it merged lanes.” At the administrative hearing, Burton testified that in the two-lane segment of the highway there was a passing lane on the left, but she was traveling in the right lane, and when the two lanes became one, “the left lane disappeared.” She said that she passed a sign which said that the lanes were going to merge, but there was no evidence of signage indicating that one lane was terminating and one continuing.
We are persuaded that there is merit in Burton’s contention that Section 49-808(1) is unconstitutionally vague as applied in this circumstance, for the statute does not clearly indicate that a signal is required when two lanes merge with neither lane clearly ending and neither clearly continuing. This situation differs significantly from that where one of two lanes ends and the other continues, as occurred in Deivbre. In the Dewbre circumstance, the statute plainly requires a signal because a driver in the terminating lane must change lanes in order to continue travel on the highway, and changing lanes constitutes a move to the left or right. But when there is no basis to discern that one lane is terminating and the other surviving, but rather the two blend into a single lane, it is not clear that the continued forward movement of a vehicle from either of the two lanes into the emerging lane constitutes a “move ... right or left” that is subject to the Section 49-808(1) signal requirement.
This vagueness in application occurs because the statute does not specify how much or what type of movement to the left or right is necessary to trigger the duty to signal. Admittedly, a very literal interpretation of the statute might lead to a conclusion that a signal is required when two lanes simply merge because a driver in either lane must move the steering wheel at least slightly in order to steer into the emerging lane. But the statute cannot reasonably be given an utterly literal application to every type of side-to-side movement, for a vehicle literally moves to the left or the right when a driver weaves a bit within his or her lane or simply negotiates a bend in the road, but no one would contend that a signal is required in those instances.
It is simply not apparent from the language of Section 49-808(1) whether a signal is required when two lanes blend into one. Persons of ordinary intelligence can only guess at the statute’s directive in this circumstance. Therefore, the statute is unconstitutionally vague as applied to Burton’s conduct.
*750Because Section 49-808(1) could not be constitutionally applied to her, Burton has shown that no legal cause existed to effectuate the traffic stop that led to her breath tests. We therefore reverse the district court’s decision affirming the administrative suspension of Burton’s driver’s license. Costs on appeal to appellant.
Judge MELANSON concurs.. The void-for-vagueness doctrine applies to statutes employing civil sanctions for violations, but the standard of certainty is less stringent than that for criminal statutes. Village of Hoffman Estates v. Flipside, 455 U.S. 489, 498-99, 102 S.Ct. 1186, 1193-94, 71 L.Ed.2d 362, 371-72 (1982); Winters v. New York, 333 U.S. 507, 515, 68 S.Ct. 665, 670, 92 L.Ed. 840, 849 (1948).