What was the specific trap being set for Jesus by the Pharisees in John 8?

Question

In the story of the woman caught in adultery, John indicates that the question of the Pharisees was a "trap".

2 At dawn he appeared again in the temple courts, where all the people gathered around him, and he sat down to teach them. 3 The teachers of the law and the Pharisees brought in a woman caught in adultery. They made her stand before the group 4 and said to Jesus, “Teacher, this woman was caught in the act of adultery. 5 In the Law Moses commanded us to stone such women. Now what do you say?” 6 They were using this question as a trap, in order to have a basis for accusing him.
John 8:2-6 (NIV)

What specifically was the trap they were trying to get Jesus to fall into?

Answer 1

At this time in history Israel was under the rule of the Romans. The Jewish law required that a woman caught in adultery was to be stoned to death.

Leviticus 20:10 NIV

“‘If a man commits adultery with another man’s wife—with the wife of his neighbor—both the adulterer and the adulteress are to be put to death.

But under Roman law a person could only be put to death by the judge, otherwise it was murder. Much like our law today. Christ did not have the "authority" as a man under Roman law to sentence anybody to death.

Thus, if Christ had answered that the woman was to be stoned He would have be breaking the Roman law. Not only this, but the act of stoning this woman would have gone against the mercy, grace and forgiveness that He had been preaching about.

But if He answered to let the woman go, then He would not have been upholding the Jewish law. Christ himself had been teaching the people that whoever loves God will obey God. So to not Stone this woman would mean that Christ was not in obedience to God, which is also a sin.

Answer 2

They wanted to get Jesus in trouble with them (disregarding Moses' Law) or with the Roman government -- or both, if possible.

Adulterers were to be put to death, but the Law required two witnesses minimum to prosecute and convict before executing -- or at least two witnesses to cast the first stones (Deut 17:7). I'm not sure how easily the adultery was proven. Note that the man involved in the adultery was not recorded as being brought to Jesus, only the woman. It's possible that the law-professors set up the adultery situation themselves, laying a stumbling block in her path in order to lay a different one in Jesus' path.

Answer 3

This seems like a good place to start: http://www.gospeldoctrine.com/NewTestament/John8.htm

From the article:

"Christ’s mission was a mission of mercy and not judgment."

If Jesus tells them to carry out the law and stone her, he is not being merciful. If he shows mercy, he is construed to be disobeying the law God handed down in Leviticus. Whichever action he chose, in the Pharisees' minds, would enable them to accuse him of doing wrong.

Answer 4

I realize another answer has been accepted, but I doubt that the Pharisees really did what is reported. In my view, the reason the Pharisees are reported to do this is because at the time the story was written or inserted, there was a controversy in the church over whether the church was only for saints, or whether it should include sinners as well. The Pharisees represent churchmen who wanted to exclude habitual sinners. Jesus represents those who wanted to include them. The former view is represented for example by The Shepherd of Hermas, a highly popular work which warns that sins after baptism will not be forgiveness. The latter by the emerging tradition of confession and forgiveness of post-baptismal sins.

The story does not exist in the earliest manuscripts. Manuscript History and John 8:1-8:11 by Chris Keith reports:

Interestingly enough, the earliest manuscripts of the Gospel of John do not contain this beloved passage. Indeed, the first manuscript to contain the story is from around 400 C.E. Around 4% of Greek manuscripts that include the passage place it in locations other than John 8:1-8:11; the earliest of these is from around the ninth and tenth centuries C.E. This perplexing manuscript history fuels debates about whether the story was originally in John’s Gospel and, if so, where. The majority of scholars believe a later Christian scribe inserted the passage into John’s Gospel at John 8:1-8:11

It is debatable whether the Pharisees of this time would have had women stoned for adultery. The Gospels are our main source for the issue of capital punishment in the 1st c. so we can't say for certain, but the Talmud quotes 2nd c. rabbis as being against it. The Talmud states:

A Sanhedrin that executed one person in a week is called a “murderous” [court]. Rabbi Elazar ben Azarya states: “Even one person in 70 years [would be denoted a murderous court].” Rabbi Tarfon and Rabbi Akiva state: “If we had been members of the Sanhedrin, no defendant would ever have been executed.”

So IMO the answer to the question is that the story was not part of the original Gospel of John and the reason these Pharisees try to trap Jesus is that the author [or the person who inserted the story] wanted to portray exclusivist churchmen of his day as heartless while portraying his inclusive view as in line with what Jesus would have done.