Difference between medical device status: CE mark versus FDA approval
Medical Device CE Guidances are available at http://ec.europa.eu/growth/sectors/medical-devices/guidance/index_en.htm  and the relevant council directive is at http://ec.europa.eu/growth/sectors/medical-devices/guidance/index_en.htm  

Regs differ by class of device, but the Class 1 guidance states 


  Devices must be designed and manufactured in such a way that, when used under normal conditions of use and for the purposes intended by
  the manufacturer, they will not compromise the clinical condition or
  the safety of patients or the safety and health of users or other
  persons, provided that any risks which may be associated with their
  use constitute acceptable risks when weighed against the benefits to
  the patient and are compatible with a high level of protection of
  health and safety.


In general, my unconfirmed understanding is that CE is safety and FDA is safety and efficacy (I'm sure about the FDA, not the CE), and that its usually simpler to get a device through CE.  When a lack of efficacy puts the safety and health of a user at risk, I believe this falls under CE purview, but for the small stuff, efficacy is caveat emptor.  

I may have CE wrong, but I think I've linked you to the resources to pore through that can set you right.  Good luck!

IIRC, one case where FDA regs/enforcements saved the US consumer's butt was leaky breast implants.  A search for this issue didn't bring me to the heart of that issue, but http://www.consultingroom.com/Blog/269/breast-implants:-what-is-the-difference-between-the-ce-mark-&amp;-fda-approval? (a fine implant manufacturer, so far as I know), suggests that medium class devices require no clinical data in the CE, but do for the FDA.  Actually, I know class 2 devices in the US might or might not need clinical data to support a 510K application for substantial equivalence.