filed a concurring opinion.
I concur in the judgment of the court. I agree with the majority’s general statements of the law concerning the community caretaking doctrine. I respectfully disagree with the majority’s conclusion that Officer Benson’s initial stop of appellant was not objectively reasonable. However, even if the stop were objectively reasonable under the totality of circumstances, the officer’s subjective motive for that stop shows that he was not engaged in community caretaking. Appellant’s initial detention cannot be justified, after the fact, as an exercise of his community caretaking duties when he did not actually have that purpose in mind. Therefore, I concur in the result but not in the analysis that led the majority to its conclusion.
Law enforcement officers frequently engage in public service activities which are wholly distinct from their duty to detect, investigate, and prevent crime. The United States Supreme Court has categorized those as “community caretaking functions.” 1 In fact, the community caretak-ing doctrine is a broad term for three separate doctrines: 1) the emergency aid doctrine;2 2) the automobile impoundment and inventory doctrine;3 and 3) the public servant doctrine.4 Each one of these doc*280trines acts as an exception to both the warrant requirement and the probable cause requirement of the Fourth Amendment.
The common thread in each of these exceptions to the warrant and probable cause requirements is the officer’s purpose. He is not acting in his “crime-fighting” role; his purpose is not to investigate crime or find evidence. Rather, his primary concern is for the public welfare or the protection of a person’s physical safety or personal property.5 As Professor LaFave has stated it:
The policeman, as a jack-of-all emergencies, has “complex and multiple tasks to perform in addition to identifying and apprehending persons committing serious criminal offenses”; by default or design he is also expected “to aid individuals who are in danger of physical harm,” “to assist those who cannot care for themselves,” and “to provide other services on an emergency basis.” If a reasonable and good faith search is made of a person for such a purpose, then the better view is that the evidence of crime discovered thereby is admissible in court.6
Thus, when a police officer detains a person or searches a person or property, not because the officer suspects criminal wrongdoing, but because he is engaged in one of these community caretaking activities, the officer’s “suspicionless” conduct may be reasonable under the Fourth Amendment. Courts must examine both the officer’s subjective belief that the care-taking is necessary and whether his conduct is objectively reasonable under the totality of the circumstances.7 If his subjective purpose is to investigate crime or gather evidence for a criminal charge, he is not acting as a community caretaker and these doctrines cannot be used, post hoc, to justify his conduct.8 Even when the officer subjectively believes that the care-taking activity is necessary, if his belief is not objectively reasonable, conduct which *281would otherwise violate the Fourth Amendment cannot be justified as community caretaking.9
In Wright v. State,10 this Court set out a list of four non-exclusive factors to assist in deciding whether a police officer acted reasonably when he temporarily detained a person to determine if that person needed assistance. The majority recites these factors and concludes that it was not objectively reasonable to believe that appellant required assistance.11 I disagree. I believe that the trial judge, based upon the facts in this case, could have concluded that Officer Benson’s act of temporarily stopping appellant was objectively reasonable as an attempt to assist a late-night motorist who might be falling asleep at the wheel. I concur in the result, however, because it is clear from the record that Officer Benson did not, in fact, stop appellant for this reason. It is apparent from the record that Officer Benson stopped appellant to investigate what he believed was a crime.
Officer Benson testified that he is a canine drug interdiction patrol officer and that he was parked along 1-20 that night for that purpose. He had his radar on and his dog in the back seat. Office Benson explicitly agreed that he was “going to detain [appellant] for the purpose of investigating” his slow driving and crossing over the shoulder of the road for twenty feet. He stated that he stopped appellant for committing an offense: failure to maintain a single lane. This is not community caretaking; this is crime investigation.12 Officer Benson turned on his patrol car video camera and videotaped the entire event. This is not community caretaking; this is evidence collecting and preservation. That is not to say that Officer Benson’s conduct was necessarily a violation of the Fourth Amendment,13 but merely that it clearly was not motivated by any “public servant” purpose.
Although an appellate court may uphold a trial court’s ruling on any legal basis or theory supported by the evidence and the applicable law, the evidence here simply does not support a finding that Officer Benson was acting as a “jack-of-all-emergencies” in stopping appellant. The “community caretaker” justification for Office Benson’s actions was not raised in the trial court and the trial judge did not make any finding that the purpose of Officer Benson’s stop of appellant’s car was to inquire about and provide assistance to a motorist in distress. Neither a trial nor appellate court may assign a subjective good faith purpose to a witness’ conduct that the witness never said he had. Thus, Officer Benson’s conduct cannot now be justified as appropriate community caretaking.
*282Therefore, I join in the judgment of the majority.
. See Cady v. Dombrowski, 413 U.S. 433, 447, 93 S.Ct. 2523, 37 L.Ed.2d 706 (1973) (recognizing a justification for a search to protect the general public); see also Terry v. Ohio, 392 U.S. 1, 13, 88 S.Ct. 1868, 20 L.Ed.2d 889 (1968) (noting that encounters between the police and citizens vary widely in purpose and may be unrelated to criminal prosecution).
. See Mincey v. Arizona, 437 U.S. 385, 392, 98 S.Ct. 2408, 57 L.Ed.2d 290 (1978) (noting an exception to the warrant requirement for emergencies, such as entering a house to attempt to save the life of a homicide victim, but holding that there is no "crime scene” exception to the warrant requirement; once the emergency dissipates, officers are required to obtain a search warrant).
. See Cady, 413 U.S. at 441, 443, 447, 93 S.Ct. 2523; see also South Dakota v. Opperman, 428 U.S. 364, 366, 96 S.Ct. 3092, 49 L.Ed.2d 1000 (1976). This exception encompasses two steps involving the Fourth Amendment. The first is the initial impoundment of the car — the restraint — and the second is the resulting inventory search — the intrusion. Part of the Supreme Court’s rationale for upholding the impoundment/inventory prong of the community caretaking doctrine in Opperman was that: "there is no suggestion whatever that this standard procedure, essentially like that followed throughout the country, was a pretext concealing an investigatory police motive.” 428 U.S. at 375, 96 S.Ct. 3092.
.See Cady, 413 U.S. at 436-37, 447, 93 S.Ct. 2523 (noting that police were simply responding to a traffic accident rather than seeking to implicate the defendant in a crime; initial encounters in such situations satisfy the Fourth Amendment’s reasonableness standard because they lack any crime-investigation purpose).
. That is not to say that the officer must be entirely pure in motive. He may hope that the murder suspect is still on the scene when he enters the house seeking to save the shooting victim. He may hope that the inventory search turns up some incriminating evidence. He may hope that the stranded motorist waving for attention is an escaped convict. But in each instance the subjective good faith purpose for his conduct is to perform a "care-taking” function, not a crime-fighting function.
. Wayne R. LaFave, Search and Seizure § 5.4(c) at 345 (1978) (quoting ABA Standards Relating to the Urban Police Function § l.l(b)(1973)).
. See, e.g., Brimage v. State, 918 S.W.2d 466, 483 n. 16 (Tex.Crim.App.1996) (when officers themselves "were under no delusion that their search was in response to an emergency,” their conduct could not be upheld under emergency doctrine; noting that with invocation of emergency doctrine " 'it is essential that courts be alert to the possibility of subterfuge, that is a false claim of such a purpose where the true intent is to seek evidence of criminal conduct’ ”) (quoting LaFave, supra, § 6.6(a), at 706).
.The subjective good faith of the officer in the community caretaking context is not inconsistent with the "pretext stop” doctrine set out in Whren v. United States, 517 U.S. 806, 809-10, 116 S.Ct. 1769, 135 L.Ed.2d 89 (1996). The decision to stop an automobile is generally deemed to be constitutionally reasonable when an officer has probable cause to believe that a traffic violation has occurred, regardless of-his subjective "bad faith” and underlying purpose to search for evidence of another crime. The community caretaking doctrine acts in reverse:’ the officer does not have probable cause to believe that the person stopped has committed a crime, but the detention is reasonable under the Fourth Amendment if the officer has subjective good faith and an objectively reasonable belief that the person detained is in need of immediate assistance.
. In Wright v. State, 7 S.W.3d 148 (Tex.Crim. App.1999), this Court stated: “[a]s a part of his duty to ‘serve and protect,’ a police officer may stop and assist an individual whom a reasonable person — given the totality of circumstances — would believe is in need of help.” Id. at 151.
. Id.
. See ante, op. at 277.
. Officer Benson did testify that this section of 1-20 contained concrete columns and that it was a potentially dangerous stretch of road. He also said that he was concerned that possibly appellant could be either intoxicated or fatigued. But those concerns were not the reason he stopped appellant. They were circumstances which might have justified his actions, but they were not the rationale for his initial detention.
.In this petition for discretionary review, we are not called upon to decide whether Officer Benson had probable cause to stop appellant for failing to maintain a single marked lane of traffic. See Tex. Transp. Code § 545.060.