<Table> <Tr> <Th_colspan="2"> Chief Justice of the United States </Th> </Tr> <Tr> <Td_colspan="2"> </Td> </Tr> <Tr> <Td_colspan="2"> Incumbent John Roberts since September 29, 2005 </Td> </Tr> <Tr> <Th> Style </Th> <Td> The Honorable (formal) Mr. Chief Justice (informal) Your Honor (when addressed directly in court) </Td> </Tr> <Tr> <Th> Appointer </Th> <Td> Presidential nomination with Senate confirmation </Td> </Tr> <Tr> <Th> Term length </Th> <Td> Life tenure </Td> </Tr> <Tr> <Th> Constituting instrument </Th> <Td> U.S. Constitution </Td> </Tr> <Tr> <Th> Inaugural holder </Th> <Td> John Jay as Chief Justice of the Supreme Court September 26, 1789 </Td> </Tr> <Tr> <Th> Formation </Th> <Td> March 4, 1789 </Td> </Tr> </Table> <Tr> <Th_colspan="2"> Chief Justice of the United States </Th> </Tr>

Who is the chief justice of the united states