delivered the opinion of the Court.
We are here presented with the question whether the Fourth Amendment requires that a lawfully seized defendant must be advised that he is “free to go” before his consent to search will be recognized as voluntary. We hold that it does not.
This case arose on a stretch of Interstate 70 north of Dayton, Ohio, where the posted speed limit was 45 miles per hour because of construction. Respondent Robert D. Robi-nette was clocked at 69 miles per hour as he drove his car along this stretch of road, and was stopped by Deputy Roger Newsome of the Montgomery County Sheriff’s Office. New-some asked for and was handed Robinette’s driver’s license, and he ran a computer check which indicated that Robinette had no previous violations. Newsome then asked Robinette to step out of his car, turned on his mounted video camera, issued a verbal warning to Robinette, and returned his license.
At this point, Newsome asked, “One question before you get gone: ]A]re you carrying any illegal contraband in your *36car? Any weapons of any kind, drugs, anything like that?” App. to Brief for Respondent 2 (internal quotation marks omitted). Robinette answered “no” to these questions, after which Deputy Newsome asked if he could search the car. Robinette consented. In the car, Deputy Newsome discovered a small amount of marijuana and, in a film container, a pill which was later determined to be methylenedioxymeth-amphetamine (MDMA). Robinette was then arrested and charged with knowing possession of a controlled substance, MDMA, in violation of Ohio Rev. Code Ann. §2925.11(A) (1993).
Before trial, Robinette unsuccessfully sought to suppress this evidence. He then pleaded “no contest,” and was found guilty. On appeal, the Ohio Court of Appeals reversed, ruling that the search resulted from an unlawful detention. The Supreme Court of Ohio, by a divided vote, affirmed. 73 Ohio St. 3d 650, 653 N. E. 2d 695 (1995). In its opinion, that court established a bright-line prerequisite for consensual interrogation under these circumstances:
“The right, guaranteed by the federal and Ohio Constitutions, to be secure in one’s person and property requires that citizens stopped for traffic offenses be clearly informed by the detaining officer when they are free to go after a valid detention, before an officer attempts to engage in a consensual interrogation. Any attempt at consensual interrogation must be preceded by the phrase At this time you legally are free to go’ or by words of similar import.” Id., at 650-651, 653 N. E. 2d, at 696.
We granted certiorari, 516 U. S. 1157 (1996), to review this per se rule, and we now reverse. to
per se We must first consider whether we have jurisdiction to review the Ohio Supreme Court’s decision. Respondent contends that we lack such jurisdiction because the Ohio decision rested upon the Ohio Constitution, in addition to the *37Federal Constitution. Under Michigan v. Long, 463 U. S. 1032 (1983), when “a state court decision fairly appears to rest primarily on federal law, or to be interwoven with the federal law, and when the adequacy and independence of any possible state law ground is not clear from the face of the opinion, we will accept as the most reasonable explanation that the state court decided the case the way it did because it believed that federal law required it to do so.”* Id., at 1040-1041. Although the opinion below mentions Art. I, §14, of the Ohio Constitution in passing (a section which reads identically to the Fourth Amendment), the opinion clearly relies on federal law nevertheless. Indeed, the only cases it discusses or even cites are federal cases, except for one state case which itself applies the Federal Constitution.
Our jurisdiction is not defeated by the fact that these citations appear in the body of the opinion, while, under Ohio law, “[the] Supreme Court speaks as a court only through the syllabi of its cases.” See Ohio v. Gallagher, 425 U. S. 257, 259 (1976). When the syllabus, as here, speaks only in general terms of “the federal and Ohio Constitutions,” it is permissible for us to turn to the body of the opinion to discern the grounds for decision. Zacchini v. Scripps-Howard Broadcasting Co., 433 U. S. 562, 566 (1977).
Respondent Robinette also contends that we may not reach the question presented in the petition because the Supreme Court of Ohio also held, as set out in the syllabus paragraph (1):
“When the motivation behind a police officer’s continued detention of a person stopped for a traffic violation is not related to the purpose of the original, constitutional stop, and when that continued detention is not based on any articulable facts giving rise to a suspicion of some *38separate illegal activity justifying an extension of the detention, the continued detention constitutes an illegal seizure.” 73 Ohio St. 3d, at 650, 653 N. E. 2d, at 696.
In reliance on this ground, the Supreme Court of Ohio held that when Newsome returned to Robinette’s car and asked him to get out of the car, after he had determined in his own mind not to give Robinette a ticket, the detention then became unlawful.
Respondent failed to make any such argument in his brief in opposition to certiorari. See this Court’s Rule 15.2. We believe the issue as to the continuing legality of the detention is a “predicate to an intelligent resolution” of the question presented, and therefore “fairly included therein.” This Court’s Rule 14.1(a); Vance v. Terrazas, 444 U. S. 252, 258-259, n. 5 (1980). The parties have briefed this issue, and we proceed to decide it.
We think that under our recent decision it. United States, 517 U. S. 806 (1996) (decided after the Supreme Court of Ohio decided the present case), the subjective intentions of the officer did not make the continued detention of respondent illegal under the Fourth Amendment. As we made clear in Whren, “ ‘the fact that [an] officer does not have the state of mind which is hypothecated by the reasons which provide the legal justification for the officer’s action does not invalidate the action taken as long as the circumstances, viewed objectively, justify that action.’ . . . Subjective intentions play no role in ordinary, probable-cause Fourth Amendment analysis.” Id., at 813 (quoting Scott v. United States, 436 U. S. 128, 138 (1978)). And there is no question that, in light of the admitted probable cause to stop Robinette for speeding, Deputy Newsome was objectively justified in asking Robinette to get out of the car, subjective thoughts notwithstanding. See Pennsylvania v. Mimms, 434 U. S. 106, 111, n. 6 (1977) (“We hold . . . that once a motor vehicle has been lawfully detained for a traffic violation, the police officers may order the driver to get out *39of the vehicle without violating the Fourth Amendment’s proscription of unreasonable searches and seizures”).
We now turn to the merits of the question presented. We have long held that the “touchstone of the Fourth Amendment is reasonableness.” Florida v. Jimeno, 500 U. S. 248, 250 (1991). Reasonableness, in turn, is measured in objective terms by examining the totality of the circumstances.
In applying this test we have consistently eschewed bright-line rules, instead emphasizing the fact-specific nature of the reasonableness inquiry. Thus, in Florida v. Royer, 460 U. S. 491 (1983), we expressly disavowed any “litmus-paper test” or single “sentence or . . . paragraph . . . rule,” in recognition of the “endless variations in the facts and circumstances” implicating the Fourth Amendment. Id., at 506. Then, in Michigan v. Chesternut, 486 U. S. 567 (1988), when both parties urged “bright-line rule[s] applicable to all investigatory pursuits,” we rejected both proposed rules as contrary to our “traditional contextual approach.” Id., at 572-573. And again, in Florida v. Bostick, 501 U. S. 429 (1991), when the Florida Supreme Court adopted a per se rule that questioning aboard a bus always constitutes a seizure, we reversed, reiterating that the proper inquiry necessitates a consideration of “all the circumstances surrounding the encounter.” Id., at 439.
We have previously rejected a per se rule very similar to that adopted by the Supreme Court of Ohio in determining the validity of a consent to search. In Schneckloth v. Bustamonte, 412 U. S. 218 (1973), it was argued that such a consent could not be valid unless the defendant knew that he had a right to refuse the request. We rejected this argument: “While knowledge of the right to refuse consent is one factor to be taken into account, the government need not establish such knowledge as the sine qua non of an effective consent.” Id., at 227. And just as it “would be thoroughly impractical to impose on the normal consent search the detailed requirements of an effective warning,” id., at 231, so too would it be *40unrealistic to require police officers to always inform detainees that they are free to go before a consent to search may be deemed voluntary.
The Fourth Amendment test for a valid consent to search is that the consent be voluntary, and “[v]oluntariness is a question of fact to be determined from all the circumstances,” id., at 248-249. The Supreme Court of Ohio having held otherwise, its judgment is reversed, and the case is remanded for further proceedings not inconsistent with this opinion.
It is so ordered.
Respondent and his amici ask us to take this opportunity to depart from Michigan v. Long. We are no more persuaded by this argument now than we were two Terms ago, see Arizona v. Evans, 514 U. S. 1 (1995), and we again reaffirm the Long presumption.