The normal rules for Characters in units (Page 47 of the rulebook, 'Characters as Leaders') tell you to use the highest Ld in the unit for all Leadership tests.
Since the Commissar entry doesn't say to do any differently, that's what you do.
Note that this will apply even before an execution. If the Commissar's Ld is the highest in the unit, tests are made using his Ld. If the test is failed, he'll execute the unit's commander (which is the model besides himself with the highest Ld).
|