The People bring an interlocutory appeal under C.A.R. 4.1 from an order of the county court, affirmed by the district court, suppressing the results of a roadside sobriety test and a blood alcohol test in the prosecution of the defendant, Manford Frank Helm, for drunk driving. The lower courts suppressed the test results primarily because the defendant was not forewarned that he could refuse to take the roadside sobriety test. We reverse the lower courts' rulings.
On April 23, 1980, a Glenwood Springs police officer, responding to a report of a hit-and-run accident involving a red Cadillac and a motorcycle, found both vehicles at the Hot Springs Lodge about a quarter mile from the scene of the accident.1 While the officer was examining damage to the motorcycle, the defendant, the driver of the Cadillac, approached the officer and denied *1074involvement in the accident. The officer noted that the defendant had an odor of liquor on his breath, unsteady balance, and thick, slurred speech.
The officer apprised the defendant of his grounds for believing that he had been driving under the influence of intoxicating liquor and asked him to take a roadside sobriety test. The defendant responded, “no problem.” In the course of the test, the officer observed that the defendant could not walk a straight line, turn without staggering, touch the tip of his nose, or recite the alphabet. The officer then arrested the defendant for driving under the influence of intoxicating liquor, section 42 — 4— 1202(l)(a), C.R.S.1973, and leaving the scene of an accident, section 42-4-1406(1), C.R.S. 1973, and took him to the police station.
Before administering a blood alcohol test, the officer gave the defendant the advisement required by the implied consent law, section 42-4-1202(3)(b), C.R.S.1973. The advisement stated that the circumstances which led the officer to believe that the defendant was under the influence of alcohol were:
“1.) The vehicle you were driving was involved in an accident which left the scene.
2.) You have a odor of alcohol on your person.
3.) You were unable to pass my Roadside Sobriety Test.”
After receiving the implied consent advisement, the defendant agreed to take a breathalyzer test. The officer testified that the defendant appeared to be “extremely intoxicated” and had difficulty following instructions. The test results showed a blood alcohol weight of 0.14 percent.2
The defendant moved to suppress the results of the roadside sobriety test, alleging that it violated his Fourth Amendment rights. He also moved to suppress the results of the breathalyzer test, arguing that the exclusion of roadside sobriety test results would leave the officer without sufficient grounds for having invoked the implied consent law. The county court found that the People had failed to meet their burden of showing that the defendant’s decision to take the roadside sobriety test was knowing and intelligent, and granted the defendant’s motions. The court relied on People v. Ramirez, Colo., 609 P.2d 616 (1980), which suggests that a defendant must voluntarily consent to a roadside sobriety test, and Phillips v. People, 170 Colo. 520, 462 P.2d 594 (1969), which held that knowledge that one may properly refuse to consent to a warrantless search is a prerequisite to a voluntary consent. Although the court listed the defendant’s ignorance that he could refuse to submit to the test as its major reason for finding his consent involuntary, it also considered the following circumstances: the defendant was in custody; he was not advised of his Miranda3 rights before taking the roadside sobriety test; he had only an eighth grade education; and he was extremely intoxicated and had trouble understanding simple directions.
Having suppressed the results of the roadside sobriety test, the county court also deleted the results from the grounds enumerated in the implied consent advisement. The court deemed the notice insufficient because it alleged only that the defendant left the scene of an accident and had an odor of alcohol on his breath. Therefore, the court also excluded the blood alcohol test results, concluding that the officer lacked probable cause to require the breathalyzer test.
The prosecution appealed the county court’s suppression order to the district court. That court upheld the county court order, reasoning, first, that People v. Ramirez, supra, required the county court to decide whether the defendant’s consent to the roadside sobriety test met Fourth Amendment voluntariness standards, and, *1075second, that the record supported the county court’s finding that the defendant did not voluntarily submit to the test. The district court also affirmed the suppression of the blood alcohol test results. Because the county court ruling rested on the erroneous supposition that a consent to search cannot be voluntary unless the person from whom the consent is sought knows that he may refuse permission for' a warrantless search, we reverse the district court’s order affirming the county court’s suppression of the roadside sobriety and blood alcohol test results.
Roadside sobriety tests raise issues involving the Fifth Amendment privilege against self-incrimination, People v. Ramirez, supra, and the Fourth Amendment right to be free from unreasonable searches and seizures. Delaware v. Prouse, 440 U.S. 648, 99 S.Ct. 1391, 59 L.Ed.2d 660 (1979); Pennsylvania v. Mimms, 434 U.S. 106, 98 S.Ct. 330, 54 L.Ed.2d 331 (1977); Terry v. Ohio, 392 U.S. 1, 88 S.Ct. 1868, 20 L.Ed.2d 889 (1968); Katz v. United States, 389 U.S. 347, 88 S.Ct. 507, 19 L.Ed.2d 576 (1967); People v. Ramirez, supra; Stone v. People, 174 Colo. 504, 485 P.2d 495 (1971). Ordinarily the Fourth Amendment bars searches conducted without a warrant issued upon probable cause. However, an exception to this rule has long been recognized for searches conducted with the consent of the person exercising effective control over the place searched or the article seized. Schneckloth v. Bustamonte, 412 U.S. 218, 93 S.Ct. 2041, 36 L.Ed.2d 854 (1973); People v. Savage, Colo., 630 P.2d 1070 (1981); Phillips v. People, 170 Colo. 520, 462 P.2d 594 (1969); Capps v. People, 162 Colo. 323, 426 P.2d 189 (1967).
In concluding that the defendant’s consent was involuntary and therefore ineffective, both lower courts cited our decision in People v. Ramirez, supra. Ramirez was one of several consolidated cases in which we held that because the Fifth Amendment privilege against self-incrimination is not implicated by a roadside sobriety test a person need not be given Miranda warnings before being asked to submit to a roadside sobriety test. However, two footnotes in Ramirez applied Fourth Amendment consent standards to roadside sobriety tests:
“1. We are remanding [some of the companion cases] ... to the district court for a hearing to determine whether the defendants’ consent to take the roadside sobriety test was voluntary under the Fourth Amendment standards set out infra at note 12.”
Id. at 617.
“12. The applicable standards for determining whether a defendant has voluntarily consented to performing the tests have been set out in Schneckloth v. Bustamonte, [citation omitted] and United States v. Watson, 423 U.S. 411, 96 S.Ct. 820, 46 L.Ed.2d 598 (1976). See People v. Traubert, Colo., 608 P.2d 342 (1980). In this case, however, the question of volun-tariness was not argued before this court, and, it will be treated as waived.”
Id. at 622. Relying on Ramirez, the county court addressed the Fourth Amendment issue, and ruled that a consent to a roadside sobriety test cannot be voluntary unless it is knowing and intelligent and the person from whom the consent is sought has been informed that he may refuse to take the test.4
Implicit in the use of the knowing and intelligent standard as a measure of an effective waiver of constitutional rights is the supposition that the right waived must be known. Johnson v. Zerbst, 304 U.S. 458, *107658 S.Ct. 1019, 82 L.Ed. 1461 (1938). In Phillips v. People, supra, we therefore defined a voluntary consent to search as one intelligently and freely given, and held that the “only requirement of intelligent consent is that the person giving the consent know that he may properly refuse to give his permission to a search conducted without a warrant,” Phillips v. People, 170 Colo, at 526, 462 P.2d at 597 (emphasis added).5
The county court drew on Phillips v. People for its definition of voluntary consent. However, People v. Ramirez, supra, adopts the voluntariness standards set out in Schneckloth v. Bustamonte, supra; United States v. Watson, supra; and People v. Traubert, supra. Schneckloth, decided four years after our decision in Phillips v. People, dispelled the notion that a voluntary waiver of Fourth Amendment rights must be preceded by an advisement that consent may be withheld. In Schneckloth, the United States Supreme Court held
“. . . when the subject of a search is not in custody and the State attempts to justify a search on the basis of his consent, the Fourth and Fourteenth Amendments require that it demonstrates that the consent was in fact voluntarily given, and not the result of duress or coercion, express or implied. Voluntariness is a question of fact to be determined from the circumstances, and while the subject’s knowledge of a right to refuse is a factor to be taken into account, the prosecution is not required to demonstrate such knowledge as a prerequisite to establishing a voluntary consent.”
Id. at 248-249, 93 S.Ct. at 2059. In United States v. Watson, supra, the Court extended the Schneckloth test to the subject of a custodial search:
“. . . The fact of custody alone has never been enough in itself to demonstrate a coerced confession or consent to search.” Id. 423 U.S. at 424,6 96 S.Ct. at 828.
We have followed Schneckloth on many occasions. People v. Elkhatib, Colo., 632 P.2d 275 (1981); People v. Hayhurst, 194 Colo. 292, 571 P.2d 721 (1977); see also People v. Savage, supra; People v. Lowe, Colo., 616 P.2d 118 (1980); People v. Ramirez, supra; People v. Traubert, supra. To the extent that findings of voluntary consent are limited by Phillips v. People, supra, to instances in which the person giving the consent knew that he could properly refuse to permit a search conducted without a warrant, Phillips is overruled.7
*1077In Schneckloth, the Court accommodated two competing concerns: “the legitimate need for [consent] searches and the equally important requirement of assuring the absence of coercion.” Id. 412 U.S. at 227, 93 S.Ct. at 2048. The Court pointed out that “. . . a search pursuant to consent may result in considerably less inconvenience for the subject of the search, and, properly conducted, is a constitutionally permissible and wholly legitimate aspect of effective police activity.” In People v. Hayhurst, supra, we reasoned that it was not necessary to impose on police officers an affirmative duty to warn persons of their right to refuse consent because other evidence is often adequate to demonstrate that the search was agreed to voluntarily.
This is such a case. Here, there is no evidence that the police officer made promises or used tactics which overbore the will of the defendant. There is no evidence that the officer claimed a right to conduct the sobriety test, or attempted to deceive the defendant. See People v. Hayhurst, supra. Instead the defendant promptly acceded to the officer’s request for a test. Knowledge of the right to refuse consent is not a prerequisite to a valid consent but one of many factors to be considered by the trial court.
In addition to the failure of the officer to inform the defendant that he need not consent to a roadside sobriety test, the trial judge considered, as relevant to the determination of voluntariness, such factors as the lack of a Miranda warning, the custody of the defendant, his lack of formal education and his “extreme” intoxication. Miranda warnings are not required before the administration oí a roadside sobriety test. People v. Ramirez, supra. Custody alone does not render consent involuntary. United States v. Watson, supra. Intoxication, although a factor to be considered, is not determinative of the volun-tariness of a consent to search. State v. Berry, 526 S.W.2d 92 (Mo.App.1975). The record indicates only that the defendant was forty-seven years old, intoxicated, and without much formal education; it contains no evidence that he failed to understand the request to take a roadside sobriety test.
Under the totality of the circumstances tests it is appropriate to take into account both the characteristics of the consenting person (such as youth, education and intelligence) and the circumstances of the search (such as duration and location). United States v. Price, 599 F.2d 494 (2d Cir. 1979); Mobley v. State, 335 So.2d 880 (Fla.App.1976). Because the defendant does not allege that the officer subjected him to any psychological coercion, his lack of formal education does not negate his consent. United States v. Mayes, 552 F.2d 729 ( 6th Cir. 1977).
Similarly, the defendant does not contend that he was so intoxicated that his will was overborne by coercive police tactics. United States v. Hall, 565 F.2d 917 (5th Cir. 1978). He readily agreed when asked to perform the sobriety test. Intoxication does not subvert consent if the individual is capable of giving an explanation of his actions. United States v. Leland, 376 F.Supp. 1193 (D.Del.1974); see also Ballay v. People, 160 Colo. 309, 419 P.2d 446 (1966). Here, the defendant volunteered information to the officer about his activities.
Reviewing the record as a whole, it clearly and convincingly demonstrates that, under the totality of the circumstances, the roadside sobriety test was conducted in accordance with the defendant’s “essentially free and unconstrained choice;” there was no evidence that his “will ha[d] been overborne and his capacity for self-determination critically impaired.” Schneckloth v. Bustamonte, supra 412 U.S. at 225, 93 S.Ct. at 2047; United States v. Watson, supra 423 U.S. at 424, 96 S.Ct. at 828; People v. Phillips, 197 Colo. 546, 594 P.2d 1053 (1979).8
*1078The county court suppressed the blood alcohol test because the implied con - sent advisement incorporated the results of the roadside sobriety test as one of the grounds for the officer’s belief that the defendant was driving under the influence of alcohol. Only the circumstances listed on the advisement notice may be advanced to justify an invocation of the implied consent law. Lucero v. Charnes, Colo.App., 607 P.2d 405 (1980). Because we find that the results of the roadside sobriety test are admissible, the test results, which the officer listed on the advisement notice, furnished a legitimate basis for the officer’s belief that the defendant was driving under the influence of alcohol. Thus, reasonable grounds existed for the application of the implied consent law to the defendant. It was error to exclude the results of the blood alcohol test performed on the defendant.
Accordingly, we reverse the ruling of the district court which affirmed the county court’s suppression of the results of the roadside sobriety test and the blood alcohol test.
LEE, J., concurs in the result. ROVIRA, J., specially concurs.. Apparently the motorcyclist followed the Cadillac from the scene of the accident to the lodge parking lot.
. Section 42-4-1202(2)(c), C.R.S.1973 (1980 Supp.), provides that a defendant is presumed to be under the influence of alcohol if the blood alcohol test establishes the weight of alcohol in the defendant’s blood at 0.10 percent or more.
. Miranda v. Arizona, 384 U.S. 436, 86 S.Ct. 1602, 16 L.Ed.2d 694 (1966).
. In footnote 4 of Ramirez we noted,
“An individual cannot be compelled to take a roadside sobriety test against his wishes. See Lanford v. People, 159 Colo. 36, 409 P.2d 829 (1966).”
Id. at 618. We also stated,
“... a roadside sobriety test can only be conducted with the subject’s consent and cooperation. See Lanford v. People.”
Id. at 621. As part of this interlocutory appeal, the People request us to reconsider the question of an individual’s right to refuse to take a roadside sobriety test. The issue was not raised in the trial court and is not properly before us.
. Justice Marshall, dissenting in United States v. Watson, 423 U.S. 411, 96 S.Ct. 820, 46 L.Ed.2d 598 (1976), succinctly summarized this view of the test: “. . . the Government must always show that a person who consented to a search did so knowing he had the right to refuse.” Id. at 457, 96 S.Ct. at 844. Marshall’s concern was that only a “knowing choice” adequately protects Fourth Amendment rights. Schneckloth v. Bustamonte, supra, 412 U.S. at 277, 93 S.Ct. at 2073 (Marshall, J. dissenting). See also A. L. I. Model Code of Pre-Arraignment Procedure §§ 240.2(2) and (3) (1975), which provide that before a search is undertaken when the person whose consent is sought is not in custody or under arrest, that person must be informed that he is not obligated to give such consent and that anything found may be used in evidence; and, if the person is in custody, he must be given the same warning and also informed that he has the right to counsel before deciding whether to grant or withhold his consent.
. In Ramirez we held that the defendant, although not under arrest, was in custody when he was asked to take a roadside sobriety test because the record established that he was not free to leave the area — “a significant deprivation of his freedom of action.” Id. at 619. Here the defendant Helm was not under arrest when he submitted to the roadside sobriety test. Although it cannot be ascertained from the record whether he was free to leave the area, the county court found that Helm was in custody when the test was administered. Custody should be determined on the basis of facts in the record. See United States v. Hall, 421 F.2d 540 (2d Cir. 1969).
.Although the language “consent to a warrant-less search was given voluntarily, knowingly and intelligently” appears in People v. Hayhurst, supra; People v. Wieckert, 191 Colo. 511, 554 P.2d 688 (1976); People v. Hancock, 186 Colo. 30, 525 P.2d 435 (1974); and Capps v. People, supra, these cases (including Phillips v. People, supra) actually used a totality of the circumstances test to determine whether consent to search was voluntarily given. Insofar as the cases are read to imply that knowledge of the right to refuse consent is a prerequisite to a review of the totality of the circumstances, we disapprove the implication.
. Under the totality of the circumstances test, the prosecution has the burden of proving vol-untariness by clear and convincing evidence. People v. Hancock, 186 Colo. 30, 525 P.2d 435 (1974); People v. Trujillo, 40 Colo.App. 186, 576 P.2d 179 (1977). Here the People sustained that burden.