Informed Consent for Saving Research Data

In a laboratory exercise, graduate students draw samples of their own blood and use these to perform various tests.  Afterward, the instructor tells the class that he wishes to collect their test results for use as baseline data in a clinical study.  Anyone may decline to participate, he says.  Is informed consent from the students needed?  What if, instead of their test results, the instructor also asked for the leftover blood samples?  Would it matter if the data and/or samples were unlabelled and anonymous?

R3H says:  Informed consent cannot be obtained in this circumstance and the data/samples may not be used.  Consent cannot be obtained since the consent cannot be considered free.  This is roughly analogous to general rule that a prisoner may not give informed consent because of the expectation of some benefit, even it is explicitly stated that no favoritism will be granted.  In this case there may be an element of coercion here since the perception may be that a grade will be affected, positively or negatively, as it relates to participation.  Even more particularly, in the context of a required class in which the grade is an important outcome with long term ramifications, the element of potential coercion is even stronger.  The grade depends on the good will of the instructor at some level.  There is potential for a real conflict of interest here, even if it is not perceived as such by the instructor.