(Edited to acknowledge that I can’t spell syphilis…)
After the revelation of unethical 1940s studies on sexually transmitted diseases conducted by U.S. researchers in Guatemala, the U.S. apologized, and both countries investigated the matter via their ethics bodies. (I can only find the U.S. report, though the Guatemalan report has been issued, according to press reports [translation].)
Then there’s the matter of compensation. While the U.S. government has pledged nearly $1.8 million in tightening human subject research rules and fighting sexually transmitted diseases in Guatemala (the odds of this showing up on a Senator Coburn report are non-trivial), the victims and their families have not yet been compensated.
And yes, there is a lawsuit. The U.S. government just filed a motion to dismiss, arguing immunity from the kind of class-action lawsuit filed by Guatemalans in U.S. Federal Court. The filing acknowledges the grave harm done, and indicates that there are other venues where the claims may be properly handled. With the current Guatemalan government changing in days, it seems pretty clear that the U.S. is the likeliest source for some kind of monetary restitution. When that happens is less clear.