In addition to which branch of government is requesting the information, another characteristic of executive privilege is whether it involves a "presidential communications privilege" or instead a "deliberative process privilege" or some other type of privilege. The deliberative process privilege is often considered to be rooted in common law, whereas the presidential communications privilege is often considered to be rooted in separation of powers, thus making the deliberative process privilege less difficult to overcome. Generally speaking, presidents, congresses and courts have historically tended to sidestep open confrontations through compromise and mutual deference in view of previous practice and precedents regarding the exercise of executive privilege.