Note that NEXUS and the CCS Rule are tools for physicians and there is no evidence-based research on their use in the pre-hospital setting as far as I know. However, that doesn't mean that we shouldn't promote the use good research in a closely related fields in our protocols. (Sounds like a "dah" but it is important to make explicit when advocating for change....)
Check out this research in the prestigious New England Journal of Medicine...
The Canadian C-Spine Rule versus the NEXUS Low-Risk Criteria in Patients with Trauma
http://www.nejm.org/doi/full/10.1056/NEJMoa031375
Taken from the research above"
"Conclusions
For alert patients with trauma who are in stable condition, the CCR is superior to the NLC with respect to sensitivity and specificity for cervical-spine injury, and its use would result in reduced rates of radiography."