The Soviet system used psychiatry as a weapon by diagnosing political opponents as mentally ill in order to confine them as patients instead of trying them in court. Anyone who challenged the state such as dissidents, writers, would-be emigrants, religious believers, or human rights activists could be branded with fabricated disorders like sluggish schizophrenia. This turned normal political disagreement into supposed medical pathology and allowed the state to present dissent as insanity.
Once labeled in this way, people were placed in psychiatric hospitals where they could be held for long periods without legal protections. Harsh treatments were often used to break their resolve. The collaboration between state security organs and compliant psychiatrists created a system where political imprisonment was disguised as medical care, letting the Soviet regime suppress opposition while pretending it was addressing illness rather than silencing critics.



Estimates of the 1938 Gulag Population and other corrective labor programs, from the book
“The History of the Gulag: From Collectivization to the Great Terror
Oleg V. Khlevniuk
Translated by Vadim A. Staklo”
Are about 6,000,000 total.
That’s 3.5% of the total population of the USSR in 1939.
Encyclopedia Britannica estimates a much more conservative 5,000,000.
The USA’s 0.7% doesn’t come anywhere close. Even if you ignore the numbers after The Great Purge you’re still looking at neck and neck numbers from the two, with USSR’s 1.4M being over 0.8%.