"In our 'Bible Chat' at our Catholic church this morning we were reading the various accounts of Jesus’ trial before Pilate, and we came across an exchange that has always seemed odd to me. I wanted to ask you about it because I suspect it is a translation issue, or else an issue that perhaps only native English speakers would have. In the exchange, Pilate says (in English translations) something to the effect of 'Are you the King of the Jews?' and Jesus says something to the effect of 'It is you who say so.' As a kid I always wondered what on earth Jesus was talking about, because Pilate didn’t say anything of the sort, he just asked the question. Later, as I encountered folks from other countries speaking English, I noticed that they typically asked questions by making a statement and just varying their intonation, like we might say in English 'You’re the King of the Jews?' So I figured that, in the original language, the exchange was something more akin to this, though I don’t know for sure.
       So, first question is, what is going on with this exchange that Jesus feels free to interpret Pilate’s question as a declaration of fact?
       And the second is, if in the original languages, a question is differentiated from a statement only by punctuation (in written form) or in intonation (in spoken form), something like my example above, why don’t English translators use a more understandable (uncommon but not unheard of) English construct like the example I gave above?" 

I think sometimes translators are just trying to preserve the feel, or even the ambiguity, of the original. But maybe not in this case. "You said it" might convey the feel. Jesus is certainly affirming his identity. We find the same language when he's being questioned by the Sanhedrin.

But Jesus remained silent. And the high priest said to him, "I adjure you by the living God, tell us if you are the Christ, the Son of God." Jesus said to him, "You have said so" (Matt 26:63). Lest we think Jesus is waddling or wavering, his next sentence leaves no doubt:

"But I tell you, from now on you will see the Son of Man seated at the right hand of Power and coming on the clouds of heaven" Matthew 26:63-64). And for that he was sentenced to death -- for a blasphemous claim.

In short, Jesus was affirming his identity. The construction is unusual in modern English. But not beyond our ability to understand.

There was no punctuation in the original manuscripts, as far as we know, just as there was no capitalization. This means translators, like readers, have to make certain assumptions.