Motor Vehicles Division (MVD) appeals the circuit court’s judgment reversing its order suspending petitioner’s driving privileges after he failed a chemical breath test following his arrest for DUII. We affirm.
We state the facts consistent with the findings of the MVD hearings officer. Jasper v. MVD, 130 Or App 603, 605, 883 P2d 244 (1994). Deputy Foster notified the police dispatcher that he was following a Saab vehicle, driven by petitioner, and a Geo vehicle, which appeared to be traveling together. Foster told the dispatcher that the Geo “was all over the road.” He said nothing about the Saab. Later, two police officers from another jurisdiction began following the Saab and the Geo. They confirmed that the Geo was not staying in its lane. Neither officer reported that the Saab was traveling erratically. The officers attempted to stop the Geo, but it did not immediately pull over. Next, they turned on their police cars’ lights and sirens. A “short while” later, the Saab and the Geo entered a store parking lot. The Geo immediately stopped and one officer arrested its driver. The other officer followed the Saab onto the lot, where it stopped and parked.
The officers contacted Deputy Radar, a member of a DUII detection team. Radar had listened to all of the conversations between the officers, the dispatcher, and Foster on his police radio. Radar went to the store parking lot and made contact with petitioner, who smelled of alcohol and admitted that he had been drinking. Radar administered a field sobriety test, and petitioner showed some symptoms of intoxication. Radar arrested him for DUII and asked him to take a chemical breath test. The test disclosed that petitioner’s blood alcohol level was .15 percent.
At the hearing, petitioner challenged the reasonableness of the initial stop. The state asked Radar, the only witness at the hearing, whether the officer who followed the Saab into the parking lot said why he had stopped petitioner. Radar answered:
“No. And again, I — I assumed based on the transmission of the two vehicles being together that when they pulled into the [store], the Saab immediately continued straight up *633while the [Geo] pulled that way, so the two * * * officers split off. That’s all the information I have.”
Later, the following colloquy occurred:
“Q. And was there any radio transmission at all about any unusual driving on the part of the Saab?
“A. No — no not that I heard. The only transmissions I heard regarding the Saab and [the Geo] combined was that Civil Deputy Foster had indicated he had seen both of the vehicles exit the Tippee Canoe Restaurant. * * * [A]nd at one point I recall Civil Deputy Foster indicating that it appeared that the two vehicles were travelling together. But that’s all I heard regarding the Saab * *
After the hearing, the hearings officer found:
“The two vehicles were * * * traveling westbound, with the Geo still failing to maintain its lane of travel. The Saab was still traveling in front of the Geo. Both * * * officers turned on their patrol vehicle overhead lights, later the vehicle sirens, in an attempt to stop the Geo vehicle. The Geo and the Saab continued to travel on the highway, disregarding the emergency vehicles and not yielding the right of way to emergency vehicles, a traffic infraction * * *.”
The hearings officer then concluded:
“Both vehicles were failing to yield for the overhead lights of emergency vehicles. The stop of both vehicles for an investigation of why one was being operated in the manner observed and for the infraction of both vehicles failing to yield, was legal and proper.”
Petitioner appealed to the circuit court, arguing that the initial stop was invalid. See ORS 131.615. The circuit court agreed and vacated the suspension order. MVD seeks a reversal of the circuit court judgment and reinstatement of the suspension order.
Although this is an appeal from a judgment of the circuit court, we review MVD’s order. Oviedo v. MVD, 102 Or App 110, 113, 792 P2d 1244 (1990). We review for substantial evidence and errors of law. ORS 813.450(4).
MVD argues, relying on Bish v. MVD, 97 Or App 648, 776 P2d 1320 (1989), that we should reinstate the order, because petitioner did not raise the issue of whether the initial stop was valid until after the evidentiary part of the *634hearing. That argument is based on an erroneous reading of the record. At the beginning of the hearing, petitioner’s attorney said:
“I’d like to put [the hearings officer] and Deputy Radar on notice that I’ll be challenging the reasonableness of this stop and the probable cause for the arrest, pursuant to [Bish] and Pooler v. Motor Vehicles Division[, 306 Or 47, 755 P2d 701 (1988)].”
That necessarily placed the validity of the stop at issue. Fischer v. MVD, 101 Or App 580, 582 n 1, 792 P2d 445 (1990).
Next, we consider whether the hearings officer erred in concluding that the initial stop was valid. MVD acknowledges that no evidence was presented about why the police stopped petitioner. It argues, however, that the hearings officer correctly concluded that the stop was justified, because facts presented at the hearing show that petitioner committed the traffic infraction of failing to yield the right of way to an emergency vehicle. ORS 811.145. MVD has cited no authority, and we have found none, for the proposition that, when there is no evidence about whether a police officer believed that a traffic infraction had occurred before making a stop, the hearings officer may infer from other facts the officer’s reason for making that stop.
The dissent’s reliance on State v. Matthews, 320 Or 398, 884 P2d 1224 (1994), as well as the other cases it cites, is unavailing. In fact, the holding in Matthews is consistent with our decision here. In Matthews, the Supreme Court interpreted ORS 810.410(3)(b), which defines an officer’s authority to stop and detain a motorist for a traffic infraction. During its discussion of that statute, the court said:
“[A]n officer who stops and detains a person for a traffic infraction must have probable cause to do so, i.e., the officer must believe that the infraction occurred, and that belief must be objectively reasonable under the circumstances.” 320 Or at 403.
Here, there is no evidence that the stopping officer subjectively believed that any traffic infraction had occurred. However, Matthews makes it clear that there must be some *635evidence that the officer believed that a traffic infraction occurred before stopping the driver.1 Id. at 404.
In short, “an officer who stops and detains a person for a traffic infraction must have probable cause to do so.” 320 Or at 403. The state refers us to no authority, and we find none, for the novel proposition that a hearings officer may, after the fact, manufacture a reason that justifies a stop in the absence of any direct evidence about whether the officer believed that an infraction had occurred and that such a belief was reasonable under the circumstances.
The police officer who stopped petitioner did not testify, nor did he tell Radar why he made the stop. The hearings officer’s conclusion that petitioner was stopped because he failed to yield to an emergency vehicle is pure conjecture. The hearings officer erred as a matter of law in concluding that the initial stop was lawful, because there was no evidence on which to base that conclusion.
Petitioner’s arrest and the chemical breath test was a consequence of, and depended on, the unlawful stop.
Affirmed.
Moreover, the testimony the dissent relies on as objective evidence about the circumstances of the stop is, in context, contradictory.
Radar first testified:
“I * * * heard Officer Fulton indicate to the Net-4 dispatcher that they were attempting to stop the Geo Tracker, but the vehicle wasn’t pulling over. A minute or two later, I then heard Officer Fulton indicate that they were attempting to use both fights and siren. A short while later Officer Fulton came back on the air and indicated that both the Saab and the Geo Tracker had pulled into a Thriftway Restaurant * *
Later the hearings officer asked Radar about the radio transmissions that he had heard, and Radar said:
“[T]he first transmission I heard was [that] * * * we’re with [the Saab and Geo]. A short while later, I then heard Officer Fulton indicate to the dispatch that they were going to attempt a traffic stop to get the vehicle stopped. Then a short while later, I heard Officer Fulton notify the dispatcher that the vehicles aren’t stopping. They’re not responding to fights or sirens. And then a short while later they’re pulling into the Thriftway * * (Emphasis supplied.)
In context, Radar’s testimony suggests that Fulton attempted to stop the Geo, and, a “short while later,” both vehicles pulled into a parking lot. Without more, that vague description of the time that preceded the Saab’s response to the police cars ’ fights and sirens provides insufficient objective evidence of what facts the stopping officer relied on to make the stop.