Details of the cases are often secret, but notorious precedents include the tobacco giant Philip Morris suing Australia and Uruguay for putting health warnings on cigarette packets.
Protesters wear masks of U.S. President Barack Obama and German Chancellor Angela Merkel as they demonstrate against Transatlantic Trade and Investment Partnership (TTIP) free trade agreement before the opening ceremony of the Hannover Messe in Hanover, Germany April 24, 2016 (REUTERS)
Obama has described national laws and protections as “regulatory and bureaucratic irritants and blockages to trade.”
In Hanover, he used a speech alongside the German Chancellor Angela Merkel to make a renewed push for the treaty to be signed.
“Angela and I agree that the United States and the European Union need to keep moving forward with the Transatlantic Trade and Investment Partnership negotiations,” he said.
“I don't anticipate that we will be able to have completed ratification of a deal by the end of the year, but I do anticipate that we can have completed the agreement.”
Tens of thousands of protesters turned out to demonstrate against TTIP ahead of Obama’s visit.
Trade unions, consumer protection groups and environmentalists said they drew a crowd of 90,000 people to demonstrate on the streets of Hannover on Saturday, although local police claim it was closer to 30,000.
Merkel insisted TTIP would not override citizens' rights or interests. In a video statement on Saturday, she described TTIP as a "win-win situation" that "could set global standards" by creating a free trade area unlike any before it.