Situation, player makes illegal move, opponent stops clock and calls TD to assess a penalty. Someone tell me what penalty is assessed in a sudden death, with less than a minute remaining on the clock. 
Under what rules?
Alex Relyea
To be specific about what “rules” are to be used, is the tournament:
a) regular rated, USCF
b) USCF Quick Chess
c) USCF Blitz
d) USCF Scholastic Blitz
e) FIDE rated
f) FIDE Rapid
g) FIDE Blitz
h) Other - unrated, 3D chess, Chinese Chess, Shogi, Klingon Chess, etc.
The answer you give determines which version of the rules will apply. Using the term “illegal move” is only the beginning of the process. At one time chess used to be simple. Now it is not. You start with a set of facts and assumptions, then figure out how to apply the appropriate rule. The implication is that not enough facts are available to determine which rules are to be used.