- "vulnerable populations"
- "research subjects"
- "human experimentation"
- "informed consent"
- ethics
- research
Combine with population-specific terms:
- prisoners
- children
- fetus
- minorities
- students
- homeless
- sex workers (**note that the offensive term 'prostitute' is still used as a subject heading)
- uninsured
- rural
- inner city
- addicts
- poor
- veterans
Also consider searching for historical situations when informed consent was not given:
- Nuremberg Trials
- Tuskegee Syphilis Study
- Milgram Experiment
- Willowbrook Hepatitis Study
- Tearoom Sex Study