Johns Hopkins University behavioral biology professor Roland Griffiths struggles with the same ethical questions when he studies the chemicals behind hallucinogenic mushrooms.

MSN: Scientist haunted by misuse of drugs he invented

Rather than a traditional trial setup, his patients pay tens of thousands of dollars for the privilege of participating in the studies (not the most ethical or effective subject selection strategy).

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Khan says drug studies in suicidal patients are possible and ethical.

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But all clinical research studies have to go through very strict ethical and regulatory checks before they get anywhere near a patient, and the UK has one of the best records world-wide for patient safety.

BBC: The 'myth' of the clinical trial guinea pig

Agents, even if working for the seller, do have some ethical duties to buyers, adds Alan Strudler, professor of legal studies and business ethics at Wharton.

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Many studies indicate that the most skilled workers prefer to work for ethical companies.

FORBES: Magazine Article