 Bracketing the question of individuals who cannot consent, many of the limitations on clinical research apply to research with competent adults. How might these limitations be justified? One approach would be to essentially grant the Libertarian analysis on theoretical grounds, but then argue that the conditions for its implementation are rarely realized in practice. In particular, there are good reasons, and significant empirical data, to question how often clinical research actually involves participants who are sufficiently informed to provide valid consent. Even otherwise competent adults often fail to understand clinical research sufficiently to make their own informed decisions regarding whether to enroll (Flory and Emanuel 2004).