The use of a private email server by Hillary Clinton for conducting email communications in her capacity of Secretary of State; and her subsequent evasion and obstruction in turning over such communications and records is an apparent in violation of US Code Title 18 Part 1 Chapter 101 Section 2071 (both (a) and (b)).
To publicly demonstrate transparency and accountability of US Government officials, the Attorney General's office must launch an investigation and seek the evidence required to prosecute this apparent violation of US law.
The very legitimacy of any government administration is dependent on the impartial and transparent upholding of US law.
"...justice should not only be done, but should manifestly and undoubtedly be seen to be done."
Ignorantia legis neminem excusat.