Yes, because a random Spanish judge will convince the US government to fork over very touchy information on a highly controversial installation.
Well...then if the US doesn't, Spain hauls Yoo, Gonzales, and Addington off to be charged with war crimes.
Then comes the tricky question of how. Domestic Spanish law enforcement has no jurisdiction in the United States and a military deployment is out of the question. Don't expect the UN to be of much use, since any motion to have an international force arrest the men would be shot down in the Security Council by the US. From a practical standpoint, it just means that Yoo, Gonzales, and Addington won't be able to travel to the European Union. While I don't keep up with their travel arrangements, something tells me that continental Europe isn't high on any of their lists for vacation destinations.
One trouble with international law enforcement is that individual nations tend to shield their citizens, especially those who are (or were once) powerful, whether they deserve to be shielded or not.