There are apps that require access to assistive devices in Yosemite.  A perfect example of this is TextExpander 4.  It needs the ability to type text on the user’s behalf.  The easiest way to enable access for these items is to drag-and-drop them into the Accessibility section under the Privacy tab in the Security and Privacy pane of System Preferences.

This can also be done from the command line via tccutil.py:

sudo tccutil.py --insert com.smileonmymac.textexpander 
sudo tccutil.py --insert com.smileonmymac.textexpander.helper

Or you can manually add items using sqlite3 , but the syntax is a little more cumbersome:

sudo sqlite3 /Library/Application\ Support/com.apple.TCC/TCC.db "INSERT INTO access VALUES('kTCCServiceAccessibility','com.smileonmymac.textexpander',0,1,1,NULL);"

It is also more difficult to enable, disable, or remove items, which is why I use tccutil.py:

List existing entries in the Accessibility database

sudo tccutil.py -l

Enable or disable TextExpander

sudo tccutil.py -e com.smileonmymac.textexpander 
sudo tccutil.py -d com.smileonmymac.textexpander

Remove Chrome from the Accessibility database

sudo tccutil.py --remove com.google.chrome

tccutil.py works great for scripting or mass deployment of settings in an enterprise environment.