Sanhedrin 120

2:
The Reisha of our mishnah posits a situation in which Re'uven commits a capital offence, let's say that he murdered someone. The punishment for murder, as we have learned in this chapter, is death by decapitation. Let's say that to begin with Re'uven was not apprehended because the murder was unsolved. Subsequently Re'uven commits another offence, let's imagine homosexual rape. This time Re'uven is apprehended and found guilty on both charges, it having become clear in the meantime that he was the murderer as well. Now, as we have already learned in Chapter Seven, Mishnah Four [Sanhedrin 091 and the following shiurim], the punishment for homosexual rape is stoning. In the previous mishnah [Sanhedrin 119] we learned that there is a hierarchy of severity in the four modes of capital punishment. The severity, it would seem, is judged by the pain and suffering which the condemned will suffer (though I suppose that this was never put to any kind of scientific test). Stoning was held to be the severest mode of execution, followed by burning, decapitation and strangulation in that hierarchical order. We can now understand the dilemma which is the subject of the Reisha of our mishnah: should Re'uven be executed by the severer mode, stoning, on account of the homosexual rape, or should he be executed by decapitation on account of the murder which has chronological priority? Our mishnah teaches that the severer form of execution is to be applied in such cases.

3:
The Seifa [last section] of our mishnah deals with a different topic. What happens if our hapless Re'uven commits one offence but in doing so manages to incur the death penalty on two different counts? All the great commentators follow the Gemara [Sanhedrin 81a] and present the following case. The incorrigible Re'uven copulates with his mother-in-law. On the assumption that his father-in-law is still alive this involves two offences: illicit copulation with his mother-in-law and illicit copulation with a married woman. The punishment for the former offence is burning, as we learned in the first mishnah of our present chapter [Sanhedrin 115]. The punishment for the latter offence is strangulation as we shall learn in the first mishnah of Chapter Eleven. According to the hierarchy outlined in the previous mishnah for this heinous offence Re'uven must be dispatched from this world by burning, which is considered the severer mode of execution.

4:
The Gemara [Sanhedrin 81a] explains the view of Rabbi Yosé as follows (I use the scenario as explained by Rabbi Ovadyah of Bertinoro). Poor old Re'uven marries Rivkah, who is the daughter of the virtuous widow Sarah. When the insatiable Re'uven manages to seduce the now not-so-virtuous Sarah he incurs the penalty of burning (on account of his liaison with his wife's mother). Sarah subsequently marries Shim'on, but continues her liaison with Re'uven. He has now incurred the penalty of strangulation (because of Sarah's relationship to the cuckolded Shim'on). According to Tanna Kamma [the unnamed sage whose view Rabbi Yosé disputes] the scoundrel Re'uven is to be removed from this naughty world by burning, which comes earlier in the hierarchy than strangulation. Also according to Rabbi Yosé Re'uven is to be removed from this world – thus making it a little less naughty – by burning; but not because of the hierarchy of punishments but because of the chronology of the events: he incurred the penalty of burning before he incurred the penalty of strangulation. In different circumstances the law would be different. However, as far as Re'uven is concerned it makes no difference, since Halakhah follows Tanna Kamma (as it almost invariably does).