Clinical research: protection of the "vulnerable"?

In this age of evidence-based medicine, clinical research is critical for developing new therapeutics and determining the best way to use these therapies. To perform appropriate clinical research, researchers must adhere to ethical standards. These standards have developed in large part as a response to egregious violations of ethically appropriate behavior. In this respect certain populations have been identified as at risk of being treated inappropriately in medical research. Current ethical guidelines prohibit or severely limit what types of research can be performed involving these "vulnerable" populations. Although this might protect these populations, the lack of research on them might actually do harm in limiting their access to life-saving therapies. We explore the historical underpinnings of protecting the vulnerable populations and whether a newer ethical paradigm that would allow for protected research on these populations should be adopted by society.