However, I'm now in a position where I can offer some expertise of my own. The European Commission yesterday decided to refer ACTA to the European Court of Justice for a ruling on "whether ACTA is incompatible – in any way – with Europe’s fundamental rights and freedoms" (there is some dispute about exactly what the question is).
Just to step back a moment and define who the actors are here: the European Commission is the EU's executive, which has fairly strong powers to negotiate for all 27 member states on trade issues but much less on other questions (ACTA involves both of these). The European Court of Justice, based in Luxembourg, is not the same as the European Court of Human Rights, which is based in Strasbourg and is not part of the EU. The ECJ rules on whether actors within the EU have stuck to EU rules; the ECtHR has a remit on human rights which stretches from the Atlantic to Russia and Azerbaijan (the membership of the Council of Europe, a separate organisation). If ACTA were eventually passed and enforced, one could imagine appeals to the Strasbourg ECtHR, but we are far from that point.
As far as I know, there has only been one previous occasion when an envisaged EU treaty was referred to the ECJ, and it also concerned intellectual property. The 2009 draft agreement on European patents was thrown out by the ECJ, not because it curtailed rights and freedoms, but because it would have set up parallel institutions to apply EU law without being themselves subject to it (the details are technical and frankly boring). The ACTA challenge is much more ideological.
The Commission's decision to refer ACTA to the ECJ is, I think, unprecedented - the patents treaty was referred to the ECJ by member states. It is obviously the result of an extraordinary level of grass-roots action and campaigning, which saw the European Parliament rapporteur resign and mass protests in numerous European cities earlier this month. It obviously also indicates that the Commission was so internally divided that it was unable to reach an agreement on the issue. On the one hand, the referral takes the decision out of the democratic process and puts it into the court system; but on the other, it certainly holds up the implementation of ACTA for at least a year, probably two, and will deliver a firm legal decision at the end of the process which will either kill ACTA completely (as the ECJ did with the patent agreement) or will restrict its applicability.
Now for the words of warning. I'm not a lawyer, I'm a political activist; and I have myself been involved with two cases which involved the European Court of Justice, neither of which, frankly, was successful. I have observed that the Court will tend to take a rather protective view of EU treaties and procedures. ACTA opponents who want to influence the court will therefore need to i) identify EU-specific concerns, rather than issues of general human rights and justice, which apply to the agreement, and ii) much more importantly identify someone who can put that particular case before the Court. My suspicion is that the only bodies with locus standi in this procedure will be the EU institutions (the Parliament and the Commission) and the 27 member states. I would recommend that ACTA activists identify friendly member state governments now, and start lobbying them immediately to make sure that their interpretation is laid before the court; and even then it may not work. My contact details are easy to find, and I will be happy to discuss further with interested parties.