It's important to note that this study, though massive, does not prove causation between drinking coffee and living longer; rather, it points to a correlation. (mindbodygreen.com)
The two cases illustrate the difficulty of proving causation and damages in large pharmaceutical cases. (indianainjuryblog.com)
First, proving causation between the words complained of and any loss sustained may be difficult. (newlawjournal.co.uk)