Support for the death penalty is at a four-decade low among the American public, but that may be of little consequence in the struggle over the future of capital punishment. That’s because the death penalty is the practice not of the nation, but rather of a handful of states.

The federal government is a minor player in criminal justice, housing just 1 in 8 inmates. The federal government executed two prisoners on the same day in 1957, but implemented capital punishment only four times in the 60 years since. It’s states that charge and sentence almost all the individuals who commit the crimes that lead to capital sentences (e.g., murder). And, more specifically, it’s just five of those states that are the true force behind capital punishment, accounting for 90 percent of the 122 executions carried out in the past three years.

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Stanford Law School Professor Robert Weisberg points to state-specific processes and incentives as drivers of the death penalty in a subset of conservative states. Most notably, he says, “Texas has elected judges. It is also located in the prosecutor-friendly 5th Circuit Federal Court of Appeals. Although the Supreme Court occasionally slaps down the Texas Court of Criminal Appeals and its federal accomplice, the Fifth Circuit, for allowing egregiously unfair capital trials, on the whole those lower courts have been happy to give Texas prosecutors a generously wide berth.”