Even though there are avenues in which your friend can oppose the deportation and there is no guarantee that an immigration hold will be placed on your friend--- the chances are realistically that a hold will be placed and he will be deported.  Before deportation, ICE will usually wait until the criminal matter is resolved.  If your friend bonds out before the immigration detainer is placed on him, then there is a chance that the hold will not hit until after he enters a plea or is found guilty of the underlying DUI.  Once his criminal cases is resolved, then involuntary removal proceedings will kick-in... this is where he would have the right to contest his deportation.  If he is found guilty or pleas guilty to the DUI, it will be much more difficult for him to contest deportation.