Attorneys representing potentially thousands of Guatemalans who were affected by U.S. syphilis experiments decades ago said Tuesday they will sue top federal health officials unless a system is created out of court to settle claims by the victims or their survivors.

The legal move comes after revelations last year that U.S. scientists studying the effects of penicillin in the 1940s deliberately infected about 700 Guatemalan prisoners, mental patients, soldiers and even orphans – some as young as 6, according to the lawyers. None were informed or gave consent.