Former President Bill Clinton did not appear for a scheduled deposition before the House Oversight Committee in its bipartisan investigation of Jeffrey Epstein, defying a congressional subpoena.

Committee Chairman James Comer announced plans to move forward with contempt of Congress proceedings against Clinton, noting that no Democrats attended Tuesday’s deposition.

Clinton’s attorneys argued the subpoenas were legally invalid, claiming they violated separation-of-powers principles and were unnecessary since the Clintons had already voluntarily provided information.

Videos posted by committee Republicans showed an empty chair labeled for Clinton, while Hillary Clinton, also subpoenaed, is expected to similarly challenge the subpoena, Fox News has reported.

A contempt vote could lead to criminal charges carrying up to a year in jail and fines, though some Republicans expressed skepticism that the Department of Justice would pursue the case.