Devise destroy session and sign out from controller?
if something_is_not_kosher # 1. log this event, 2. send notice redirect_to destroy_user_session_path and
Just in case someone can't use it directly.
<% if user_signed_in? %> <%= link_to "Logout", destroy_user_session_path, :method => :delete %> <% else %> <%= link_to "Sign up now!", new_user_registration_path%> <% end %>