Members of Governor Jay Nixon's staff will testify voluntarily this week before a Missouri House panel that had tried to subpoena them.
Republican Representative Stanley Cox says six current members of Nixon's administration and a former Revenue Department director will testify Tuesday and Wednesday.
The panel is investigating the Revenue Department practice of making electronic copies of birth certificates, concealed gun permits and other personal documents of applicants for driver's licenses and state IDs.
Revenue Department officials told a House committee Monday they began requiring documents such as birth certificates and concealed weapons endorsements to be scanned into a state computer system as part of an effort to deter fraud.
Lawmakers raised questions about the process after a southeast Missouri man filed a lawsuit last week challenging the new procedures.
Revenue officials said the digital copies of documents are kept by the department, and only basic information about the applicant is forwarded to a contractor that makes the licenses.
Several dozen lawmakers are backing a bill that would bar Missouri from keeping copies of the documents.