When we first meet Satan in the Bible, it is as a lawyer. (Insert obligatory lawyer joke.) “The prosecutor” is the translation of הַשָּׂטָן (haśśāṭān) preferred in Job 1-2 by Fokkelman and in Zech. 3:1-2 by Petersen. Fokkelman explains the setting of the prologue of Job:
The author opens the Book of Job in his role as omniscient narrator. That quality enables him to inform us of what goes on in the heavenly council. He lets us listen in while God is talking to an angel on duty, a sort of District Attorney.
Similarly, Zech. 3:1-2 takes place in a “courtroom setting”, a “legal context…in the divine council”:
The scene is set with השׂטן in the role of prosecutor,המלאך [hammalʾak] as the defense attorney, Yahweh as the judge, and the high priest Joshua as the defendant (3:1).
Stokes states that according to the “present scholarly consensus,” the śāṭān in the Old Testament “serves God as a sort of prosecuting attorney in the heavenly court.”
It is notable that in these two Old Testament passages (and only these two) śāṭān has the definite article: it is not merely a prosecutor, but the prosecutor. Most scholars do not regard śāṭān as a proper name in these passages, since proper names in Hebrew do not normally have the article, though it is possible. Hence śāṭān should probably be translated here and not transliterated. (This is in contrast to the New Testament, where satanas should definitely be transliterated ‘Satan’ since the writers have already transliterated it from Hebrew/Aramaic into Greek).
It is not necessarily the case that haśśāṭān in Job is the same being as haśśāṭān in Zechariah. The word refers to “a certain office in the divine council” and not necessarily a specific person, though it is likely that ancient readers with both books before them would have identified the two. Hence it is not surprising that by the time the New Testament was written, Satan is the designation of a specific being. There is a consensus that śāṭān refers to a heavenly adversary in four OT texts: Numbers 22:22-32, 1 Chronicles 21:1, Job 1-2, and Zechariah 3.
It is as a heavenly prosecutor that Satan features most prominently in rabbinic literature, as well:
The role of accuser is common to all rabbinic sources, while that of seducer is more or less restricted to the Babylonian Talmud and the Tanhuma.
These dual functions of seduction and accusation were not regarded by the Rabbis as contradictory but as complementary. In BBat 16a, a saying attributed to an anonymous Tanna states that Satan
comes down to earth and seduces, then ascends to heaven and awakens wrath; permission is granted to him and he takes away the soul.
Satan is portrayed here as an overzealous prosecutor who engages in what would be called ‘entrapment’ in a modern legal context. He induces people to sin so that he might prosecute them (and, having won his case, he also plays the role of executioner).
In the New Testament, the accusing function of Satan is nearly absent. Instead, Satan is primarily a seducer and an oppressor. Nevertheless, Satan does appear as an accuser or even prosecutor in a few New Testament passages, two of which will be discussed here.
In Luke 22:31-32, Jesus tells Simon Peter that Satan has requested permission to sift ‘you’ (ὑμᾶς, humas, plural pronoun referring to all the disciples) like wheat. Crump states, “The similarity in this with the heavenly court scenes of Job 1:8-12; 2:3-7 has been observed many times.”
The Greek verb used here, ἐξαιτέω (exaiteō), means “to ask for with emphasis and with implication of having a right to do so.” What does ‘sift like wheat’ mean, and from whom did Satan request permission to do this? In the Old Testament, the imagery of harvesting wheat is used repeatedly to describe divine judgment (Ps. 35:5; Jer. 13:24; Amos 9:9; cf. Matt. 3:12). Hence, Satan’s request for permission to sift the disciples like wheat probably means that he has brought charges against them in the hope of awakening God’s wrath so that he can execute judgment. It is the same concept reflected in the Talmud in BBat. 16a. That God is the recipient of his request for permission is confirmed by Jesus’ countermove, which is to make an intercessory prayer for Simon Peter (σοῦ, sou, singular pronoun). As Crump states, “The juxtaposition of ‘Satan has demanded…but I have asked’ (ἐγὼ δὲ ἐδεήθην) indicates that Jesus’ prayer has been specifically aimed at effectively countering Satan’s interest.”
In this text, then, we have Satan functioning as a prosecutor and Jesus as an intercessor.
Satan’s accusing function is again apparent in Rev. 12:10-11. John sees a vision of war in heaven between Michael and the dragon and their respective angels (the dragon being identified as Satan), and the dragon and his angels lose their place in heaven and are thrown down to earth. A proclamation then comes from heaven:
Now have come the salvation and the power and the kingdom of our God and the authority of his Messiah, for the accuser (ὁ κατήγωρ, ho katēgōr) of our comrades has been thrown down, who accuses them day and night before our God. But they have conquered him by the blood of the Lamb and by the word of their testimony, for they did not cling to life even in the face of death. (Rev. 12:10-11 NRSV)
Crump states concerning this passage, “The OT background is that of ‘Prosecutor’ in the heavenly court.” As in the Talmud, the picture here is of an overzealous prosecutor: he brings charges day and night. The Greek word translated ‘accuser’ is katēgōr, a diminutive form of katēgoros, a legal technical term for a prosecutor:
Katēgoros (κατήγορος) refers to the prosecutor in the Athenian court and continued to be used in the Greek East. Katēgoros is also used in the sense of a prosecutor in Josephus (Antiquities, 7.6) and in an inscription from Laconia dated to 42 CE.
The procedure of criminal trials in ancient Israel is described as follows:
Both civil and criminal actions were tried at the gate, and, undoubtedly, the selection of this place for trial was made to allow the maximum number of people to witness the proceedings. In a criminal case, the accusing party stood to the right of the accused and, in the presence of the elders (who were seated), presented his or her complaint. Although this accusation was usually given orally, it might be written. The accused person might be assisted in his or her defense by a defender, who was in fact a witness for the defense. Each of the elders sitting as a judge acted as an arbitrator in the case and might himself give evidence pertinent to the matter being tried. The accusing witness bore special responsibility for prosecuting the case, and his role was emphasized by the rule that, if the death penalty were imposed, it was he who was responsible for throwing the first stone in execution of the judgment.
It seems that in ancient Israel, the role of accuser was not generally conducted by a state-appointed professional as today. Nevertheless, whether by divine appointment or self-appointment, Satan came to be viewed as one fulfilling this function in the heavenly court on an ongoing basis.
So much for the accuser; what about the defence? Once again, in ancient Israel there were not generally professional defence attorneys available to the public. So too, “In ancient Rome, lawyers…generally did not represent private parties before the various courts.” Nevertheless, in Roman criminal procedure, the accused, “if he so desired, could choose a representative to defend him (‘patronus,’ ‘advocatus’).” The nearest equivalent of advocatus in Greek was παράκλητος (paraklētos). It has long been debated whether paraklētos is “a legal word sometimes used more generally or a word of more general meaning sometimes applied in legal proceedings”. A number of scholars and lexical authorities have argued that paraklētos is a technical term meaning something like “defence attorney”. Following Grayston’s careful study of occurrences of this rare word in ancient Greek, many scholars have accepted his conclusion that paraklētos “was a word of general meaning which could appear in legal contexts, and when it did the paraklētos was a supporter or sponsor.” However, Shelfer has more recently argued that paraklētos is a "precise calque for the Latin legal term advocatus". He holds that this meaning applies in all five occurrences in the Johannine writings.
Harvey takes a balanced view of the matter:
When (according to the traditional picture) one came before the judgment seat of God, one would find oneself facing formidable charges. Sins which one had forgotten would be brought against one; and the devil (the ‘accuser’) would be there, seeking to make one appear in the worst possible light. But there would be certain things on the other side. Good deeds might speak in one’s favour and outweigh the contrary evidence. To borrow a term from Jewish legal procedure, one would find that one had a paraclete, an ‘advocate’ (the original word paraklētos was Greek, but had been taken over into the language in the form peraqlit). In a Jewish court a plaintiff or defendant was entitled to enlist the help, not only of a witness to the facts, but of a person of high standing who might give personal support and advise the judges to believe what they were being told. This was not ‘advocacy’ in the western, professional sense: the paraclete influenced the judges’ decision, not by expertise in the law (this was the judges’ business), but by the fact of being a person enjoying the esteem and trust of society. Nevertheless the nearest word in English is probably ‘advocate’, so long as this is understood in a non-professional sense.
The word paraklētos is used several times in the Gospel of John where it refers to the Holy Spirit (John 14:16; 14:26; 15:26; 16:7), and once in 1 John where it refers to Jesus Christ (1 John 2:1). Even in the Gospel, Jesus’ promise to send “another paraklētos” implies that he too is a paraklētos, and the fact that he sends that paraklētos subordinates the Holy Spirit’s role to his own.
In the Gospel of John it is not obvious that the word is used in a legal setting; it is sometimes translated ‘Advocate’ (NIV; NET; NLT; NRSV) but also as ‘Helper’ (NASB; NKJV; ESV; ISV) or some synonym. The functions of the paraklētos in John 14-16 include: (1) dwelling within the community, he gives access to the Father; (2) teaching all things necessary for an approach to the Father; (3) mediating in relation to the community and the world; (4) proceeding against the world on behalf of the community.
However, in John 16:6-11 it is significant that the paraklētos is mentioned in connection with forensic language (sin, righteousness and judgment). It is even more significant that the explanation of how he will “prove the world wrong about judgment” is, “because the ruler of this world has been condemned.” The ruler of this world is recognized by most scholars as a designation for Satan (cf. 1 John 5:19). In John 12:31 he is said to be “cast out” in connection with Jesus’ death. This closely parallels the idea of Rev. 12:7-11, and suggests that Jesus’ death has resulted in the judgment and casting out of the katēgōr, which paves the way for the paraklētos. (Satan remains active, as detailed in Rev. 12:12-18, but now has no access to the heavenly court.)
In 1 John 2:1 the paraklētos is Jesus, and here the forensic connotation of the term is unmistakable: “But if anyone does sin, we have an advocate with the Father, Jesus Christ the righteous”. The key difference between the Holy Spirit as paraklētos and Jesus as paraklētos is that the Holy Spirit is with us whereas Jesus is with the Father. The Holy Spirit is sent by Jesus to assist believers in their earthly situation while Jesus himself intercedes for us in the heavenly court – the exact opposite of Satan’s function.
What is interesting about the words katēgōr and paraklētos is that both were borrowed into Hebrew as loanwords (קַטֵיגוֹר, qaṭēḡôr and פְּרַקְלִיט, peraqlît) and appear frequently in rabbinic literature in legal contexts referring to a prosecutor and advocate respectively, including in the context of the heavenly court. Consider the following examples:
“One single angel is an advocate (peraqlît) out of one thousand accusers (qaṭēḡôr)” (Targum Job 33:23)
“R. Eliezer ben Yaakov says, ‘One who performs one commandment acquires for himself one advocate (peraqlît) but one who transgresses one transgression acquires for himself one prosecutor (qaṭēḡôr).’” (M. Avot. 4:11)
“Michael and Sama’el are like an attorney for the defence (סַנֵּיגוֹר, saneḡôr) and a prosecutor (qaṭēḡôr) [that] stand in court. The one speaks and the other speaks. The one concludes his case and the other one likewise. [Then] the defence attorney knew he had won, and began praising the judge so that he should give the verdict. The prosecutor wished to add a point. Said the defence attorney to him: Be silent, and let us listen to the judge.” (Ex. Rabbah 18.5)
“For on all the days of the year, Satan is able to draw up an indictment, but on the Day of Atonement, Satan is not able to draw up an indictment.” (Lev. Rabbah 21.4.H)
It is probable that this Jewish notion of Michael and Satan (or Sama’el) as opposing attorneys stands in the background of the conflict described in Rev. 12:7-9 (cf. also Jude 9), which explains the use of qaṭēḡôr in 12:10. In the New Testament, Michael’s advocacy function is vestigial, having been superseded by that of the exalted Christ.
The Leviticus Rabbah text is significant because it shows that in Jewish thought, atonement was seen as a restraint on Satan’s ability to prosecute. The same idea is taken further in Rev. 12:10-11. Jesus’ atoning work was so efficacious that the Prosecutor did not merely get a day off; he was disbarred!
A last comment concerns the relationship between Jesus’ role as paraklētos and his role as eschatological judge. To our modern minds this appears to be a conflict of interest: how can a judge also serve as intercessor for a defendant? However, in ancient Israel the lines between these various juridical roles were not as clearly demarcated as they are today:
The judge… sometimes personally fulfils the task of prosecuting (like a modern police magistrate) and at other times the judge appears as counsel for the accused.
Reading through the account of the final judgment in Matt. 25:31-46, it appears that Jesus fulfils all of these functions. Or put differently, there is no need for any function besides judge because Jesus fulfils it perfectly. In the meantime, Jesus is available as paraklētos to those who seek Him by faith, while the prosecutor’s office is vacant:
Who will bring a charge against God’s elect? God is the one who justifies; who is the one who condemns? Christ Jesus is He who died, yes, rather who was raised, who is at the right hand of God, who also intercedes for us. (Romans 8:33-34 NASB)
 Fokkelman, J.P. (2012). The Book of Job in Form: A Literary Translation with Commentary. Leiden: Brill, p. 37.
 Petersen, D.L. (1984). Haggai and Zechariah 1-8: A Commentary. Louisville: Westminster John Knox Press, p. 186.
 Fokkelman, op. cit., p. 15.
 White, E. (2014). Yahweh's Council: Its Structure and Membership. Tübingen: Mohr Siebeck, p. 54. cf. cf. Bovati, P. (1997). Re-establishing Justice: Legal Terms, Concepts and Procedures in the Hebrew Bible. London: Bloomsbury, pp. 236-238.
 Petersen, op. cit., p. 190.
 White, op. cit., p. 54.
 Stokes, R.E. (2014). Satan, Yhwh’s Executioner. Journal of Biblical Literature, 133(2), 251-270. See pp. 251-252. Stokes himself disagrees with the consensus. He thinks the śāṭān’s function is that of executioner, not prosecutor.
 See discussion in Laato, A. (2013). The Devil in the Old Testament. In I. Fröhlich & E. Koskenniemi (Eds.), Evil and the Devil (pp. 1-22). London: T&T Clark, pp. 3-5.
 Laato, op. cit., p. 4.
 The consensus is less dominant concerning 1 Chr. 21:1, which lacks the article and is seen by some as referring to an anonymous human adversary; so Japhet, S. (1993). I & II Chronicles: A Commentary. Louisville: Westminster John Knox Press, pp. 373-375. Note however that Japhet acknowledges that in Zech. 3:1ff and Job 1-2 Satan is “a member of the divine entourage”, in the former case “the supernatural accuser in the divine court.”
 That this point is uncontroversial can be seen in Stokes, R.E. (2009). The Devil Made David Do It… or ‘Did’ He? The Nature, Identity, and Literary Origins of the ‘Satan’ in 1 Chronicles 21:1. Journal of Biblical Literature, 128(1), pp. 91-106. See p. 94; Brown, D.R. (2011). The Devil in the Details: A Survey of Research on Satan in Biblical Studies. Currents in Biblical Research, 9(2), 200-227. See p. 203.
 Crump, D.M. (1992). Jesus the Intercessor: Prayer and Christology in Luke-Acts. Tübingen: Mohr Siebeck, p. 154.
 Bauer, W., Danker, F.W., Arndt, W.F. & Gingrich, F.W. (2000). A Greek-English Lexicon of the New Testament and other early Christian literature. Chicago: University of Chicago Press, p. 344.
 Crump, op. cit., p. 155.
 Most manuscripts have κατήγορος. See Metzger : 673 for discussion on why the majority of the committee regarded κατήγωρ (found only in Codex Alexandrinus) as original. The words have the same meaning, so this text-critical issue has no effect on our study.
 Crump, op. cit., p. 155 n. 3.
 Following critical texts; some manuscripts have kategoros
 Hidary, R. (2012). Why are there lawyers in heaven? Rabbinic Court Procedure in Halakha and Aggada. Association for Jewish Studies Conference, p. 1.
 See Ps. 109:6; Zech. 3:1-2.
 Jones, M. & Johnstone, P. (2011). History of Criminal Justice. London: Routledge, p. 24.
 So Bovati, op. cit., p. 236.
 Andrus, R.B. (2009). Lawyer: A Brief 5000-year History. Chicago: American Bar Association, p. 139.
 Eismen, A. (1913). A History of Continental Criminal Procedure. Boston: Little, Brown, and Company, p. 23.
 Grayston, K. (1981). The Meaning of Parakletos. Journal for the Study of the New Testament, 13, 67-82. p. 70.
 Grayston 1981: 75.
 Shelfer, L. (2009). The Legal Precision of the Term 'παράκλητος'. Journal for the Study of the New Testament, 32(2), 131-150.
 Harvey, A.E. (2004). A Companion to the New Testament. Cambridge: Cambridge University Press, p. 357.
 Grayston 1981: 80.
 See my paper on the devil in 1 John for further analysis: Farrar, T.J. (2014). The Devil in the General Epistles, Part 3: 1 John. Accessed at http://www.dianoigo.com/publications/The_Devil_in_the_General_Epistles_Part_3_1John.pdf, pp. 3-5.
 Sperber, D. (1984). A Dictionary of Greek and Latin Legal Terms in Rabbinic Literature. Ramat-Gan: Bar Ilan University Press, pp. 178-179.
 trans. Sperber, op. cit., p. 180. The words here are the Aramaic equivalents of the Hebrew words, and qaṭēḡôr is of course plural.
 Hidary, op. cit., p. 1.
 This is another term for advocate, similar to peraqlît but more technical: “attorney for the defence.” It is also borrowed from Greek (συνήγωρ). See Sperber, op. cit., p. 126.
 trans. Sperber, op. cit., p. 179.
 The Hebrew word for ‘indictment’ is from the same root as qaṭēḡôr.
 Neusner, J. (2001). A Theological Commentary to the Midrash (Vol. 4). Lanham: University Press of America, p. 88.
 Bovati, op. cit., p. 236.