The European Parliament's Committee on International Trade held a workshop on ISDS on Tuesday. I had a little trouble viewing the recorded video, but try these links.
I was particularly interested in the response given by Rupert Schlegelmilch of the European Commission to the question, "Where is the weakness in the U.S. legal system?", which he restated as, "Do we need these rules for the U.S."? See 1:51:00 of the video. For his response, go to 1:52:25, where he said: "Even in the U.S., you can have bias against foreign companies." He then referred to the "Cuba policy," noting that a "trademark was confiscated," and that the EU won a case at the WTO on the issue. He also talked about "discrimination in public procurement," and noted that there is no non-discrimination principle in U.S. law.
The concerns he raises are certainly legitimate ones. But there's an issue as to how to deal with them, which leads me to this question: How would the U.S. Congress react to an investor-state lawsuit against either of these policies?