In Graham v. Florida , 560 U.S. 48, 130 S.Ct. 2011, 176 L.Ed.2d 825 (2010), the United States Supreme Court declared that it was a violation of the Eighth Amendment to impose a sentence of life imprisonment without parole upon a juvenile offender who was convicted of a non-homicide crime. In Miller v. Alabama , 567 U.S. 460, 132 S.Ct. 2455, 183 L.Ed.2d 407 (2012), the Supreme Court extended its holding from Graham to provide that murderers who were juveniles at the time of the commission of their crimes cannot not be sentenced to mandatory life imprisonment without the possibility of parole. In this appeal of a petition pursuant to Florida Rule of Criminal Procedure 3.800(a), the appellant asks us to extend the holdings of Graham and Miller to provide that his sentence for his participation in a murder, which he committed when he was an adult, is illegal.1 We will not do so. See Romero v. State , 105 So.3d 550, 552-53 (Fla. 1st DCA 2012) (finding that the defendant's life in prison sentence was not unconstitutional as he committed his crime at the age of eighteen).
The United States Supreme Court has held that there is a bright line between being a juvenile and an adult; that line is eighteen. The Court first discussed the bright line in Roper v. Simmons , 543 U.S. 551, 125 S.Ct. 1183, 161 L.Ed.2d 1 (2005). In Roper , the defendant was sentenced to death for his involvement in a murder that was committed when he was seventeen years and five months old. Id. at 557-58, 125 S.Ct. 1183. During the penalty phase, the defendant argued that he should not receive a death sentence because he had no prior convictions or charges previously filed against him, he was very immature, he was very impulsive, and he was very *1010susceptible to being manipulated or influenced. Id. at 558-59, 125 S.Ct. 1183. In determining whether the defendant's sentence violated the Eight Amendment, the Court categorically stated that juveniles are different because of their immaturity, their lack of responsibility, their greater susceptibility to negative influences and pressure, and the fact that they have fewer fixed personality traits. Id. at 569-71, 125 S.Ct. 1183. After having acknowledged those differences, the Court declared that there was a need for a bright line even though a bright line does not allow considerations for those that mature faster or slower. Id. at 574, 125 S.Ct. 1183. The Court held that because society draws the line at eighteen between childhood and adulthood, that is where the line is with regards to imposing the death penalty. Id.
Five years after Roper was decided, the United States Supreme Court reaffirmed that eighteen was the line between being a juvenile and an adult. Graham , 560 U.S. at 75-79, 130 S.Ct. 2011. This time the Court explained that it was explicitly rejecting the case-by-case approach and why. Id. at 76-79, 130 S.Ct. 2011. The Court also explained why it chose the bright line rule of eighteen. Id. at 79-84, 130 S.Ct. 2011.
The bright-line rule of when adulthood begins and childhood ends drawn by the United States Supreme Court has not been changed by the Florida Supreme Court nor has the Florida Supreme Court stated that the Florida Constitution offers a different level of protection. See e.g. Foster v. State , 258 So.3d 1248 (Fla. 2018) (declining to extend Roper to an eighteen-year-old defendant sentenced to death) (reaffirming that society has drawn the line at eighteen); Branch v. State , 236 So.3d 981, 985-97 (Fla. 2018) (declining to extend Roper to a twenty-one-year-old defendant sentenced to death); Guzman v. State , 183 So.3d 1025, 1027 (Fla. 2016) (Pariente, J. concurring) (even though there was less than a year difference between the defendants in Graham and Guzman , society must draw a line somewhere, and society consistently draws it at the age of eighteen). In fact, Florida courts must construe the prohibition against cruel and unusual punishment in conformity with the United States Supreme Court even if they were inclined to follow the direction of other courts that are deviating from the bright-line rule of age eighteen. Art. I, § 17, Fla. Const.
Even though some courts may have deviated from the bright line, society, as a whole, continues to hold the line at eighteen. At eighteen, a person is deemed mature enough to exercise the sovereign franchise.2 At eighteen, a person is mature enough to sit in judgment of his or her fellow citizens on a jury in all but five states.3 At eighteen, a person can join the *1011military without needing parental consent.4 At eighteen, male citizens are required to register for the military draft so that in times of national emergency, they may be compelled to fight and perhaps die for their country.5 With the exception of two states, at eighteen, a person acquires the unrestricted right to consent to marriage.6 Even though many states have recently enacted or proposed legislation to curtail the number of exceptions allowing minors to enter into marriage, no state has changed the age of the unrestricted right to marry.7 In all but three states, at eighteen, a person acquires the unrestricted right to enter into and be held accountable for contracts.8 At eighteen, a person obtains *1012the unrestricted right to consent to healthcare services in every state except six.9
It is well established that eighteen is the dividing line between adult privileges and responsibilities and the privileges and responsibilities of children. We decline the invitation to treat this adult murderer as a child.
AFFIRMED .
B.L. Thomas, C.J., and Osterhaus, J., concur.