Original sentence: Currently, there are two Retired Associate Justices: Sandra Day O'Connor, who assumed senior status on January 31, 2006 and  David Hackett Souter, who assumed senior status on June 29, 2009
Edited sentence: Currently, there are two Retired Associate Justices: Sandra Day O'Connor, who assumed senior status on January 31, 2006, and  David Hackett Souter, who assumed senior status on June 29, 2009