Argument: Will the investigation get anywhere; who should be prosecuted?

The biggest problem facing an investigation by a prosecutor is whether there is any point in the investigation. Who could be relevant witnesses? Would any of them cooperate? [1] Ultimately who do you prosecute? Germany might be able to bring some of the US staff in Germany who conducted the surveillance to trial but it seems most unlikely that they would be able to get anyone higher up the chain. Is the person who authorised the surveillance really likely to be extradited? It seems unlikely, so why bother?

[1] Spiegel Staff, ‘Probing America: Top German Prosecutor Considers NSA Investigation’, Spiegel Online, 20 January 2014, http://www.spiegel.de/international/europe/nsa-syping-scandal-a-944415.html

Candidate 1: "There is a big difference between justice not being done because the United States refuses to cooperate and justice not being done because German prosecutors could not get the evidence to bring charges. If the former there is at least a chance of a trial, possibly in abstention, where all the evidence can come out."
Candidate 2: "If countries will not act on narrow issues involving privacy freedoms and internet surveillance even when their head of government is on the receiving end then what hope is there for the broader picture? There is no point in proclaiming everyone should follow the law then we would have no crime if there is no mechanism to punish those who commit crime. Germany should not let the NSA get away with its actions or it will surely do the same again in the future."
Candidate 3: "A failure by the United States to agree to a no spy agreement already damages relations. One of the leaders of the SPD, Thomas Oppermann, has said “failure of the agreement would be unacceptable” and would “change the political character of relations.” [1] If the US is willing to damage relations by stonewalling then should the Germans really be considering US diplomatic feelings in the matter? The United States gains from its relations with Germany as well as the other way around. Stopping intelligence sharing as a result of a prosecution would be acting against US interests in fighting terrorism.

[1] Deutsche Welle, ‘Impasse at US-Germany ‘no-spying’ talks?’, dw.de, 14 January 2014, http://www.dw.de/impasse-at-us-germany-no-spying-talks/a-17361318"

There is a big difference between justice not being done because the United States refuses to cooperate and justice not being done because German prosecutors could not get the evidence to bring charges. If the former there is at least a chance of a trial, possibly in abstention, where all the evidence can come out.
