  A long-duration gamma-ray burst (GRB) marks the violent end of a massive
star. GRBs are rare in the universe, and their progenitor stars are thought to
possess unique physical properties such as low metal content and rapid
rotation, while the supernovae (SNe) that are associated with GRBs are expected
to be highly aspherical. To date, it has been unclear whether GRB-SNe could be
used as standardizable candles, with contrasting conclusions found by different
teams. In this paper I present evidence that GRB-SNe have the potential to be
used as standardizable candles, and show that a statistically significant
relation exists between the brightness and width of their decomposed light
curves relative to a template supernova. Every single nearby spectroscopically
identified GRB-SN, for which the rest-frame and host contributions have been
accurately determined, follows this relation. Additionally, it is shown that
not only GRB-SNe, but perhaps all supernovae whose explosion is powered by a
central engine, may eventually be used as a standardizable candle. Finally, I
suggest that the use of GRB-SNe as standardizable candles likely arises from
from a combination of the viewing angle and similar explosion geometry in each
event, the latter which is influenced by the explosion mechanism of GRB-SNe.
