Servicemembers Rights Enforcement Improvement Act of 2012

Servicemembers Rights Enforcement Improvement Act of 2012 - Amends the Servicemembers Civil Relief Act (the Act) concerning the protection of servicemembers against default judgments to require a plaintiff, before filing an affidavit, to conduct a diligent and reasonable investigation to determine whether or not the defendant is in military service, including a search of available records of the Department of Defense (DOD) and any other available information.

Makes a private right of action for a violation of the Act retroactive to December 19, 2003.

Allows a veteran on whose behalf a complaint of a violation of employment or reemployment rights is made by the Attorney General (AG) to intervene in such action, and to obtain appropriate relief. Requires the AG, within 60 days after receiving a referral of an unsuccessful attempt to resolve a complaint relating to a state or private employer, to notify the person on whose behalf the complaint is submitted of either the decision to commence such an action or of when such decision is expected to be made. Requires, in the latter case, such decision to be made within an additional 30 days. Requires the AG to commence such an action when there is reasonable cause to believe that a state or private employer is engaged in a pattern or practice of resistance to the full enjoyment of such employment and reemployment rights and benefits, and that the pattern or practice is intended to deny the full exercise of such rights and benefits.

Provides the Special Counsel with subpoena power to require the attendance and testimony of, and production of documents from, federal employees, to be enforced through the Merit Systems Protection Board.

Authorizes the AG to issue and serve a civil investigative demand for the production of documentary material relevant to an investigation under the Act.