No, the bibliography just adopts whatever was in force for the rest of
the document unless you are using a special style that makes it
unjustified (actually I usually use \raggedright for bibliographies anyway, because they often contain long unhyphenatable words).
You haven't said what packages you are using. Something is making this happen: you need to find what it is and turn it off.
If you have something preceding the bibliography that is turning justification off (eg \raggedright or \flushleft) then put it inside a group so that it terminates before the bibliography starts.
As an absolute last resort you could undo the effect of \raggedright by reversing what it does, which is defined in latex.ltx as:
\def\raggedright{%
\let\\\@centercr\@rightskip\@flushglue \rightskip\@rightskip
\leftskip\z@skip
\parindent\z@}
This is absolute, which is why \raggedright must always be used inside a group. To undo its effects, you need to re-establish the original meaning of \\ thus:
\makeatletter
\renewcommand\\{%
\let \reserved@e \relax
\let \reserved@f \relax
\@ifstar{\let \reserved@e \vadjust \let \reserved@f \nobreak
\@xnewline}%
\@xnewline}
and then set the right skip back to zero:
\@rightskip\z@skip\rightskip\z@skip
\makeatother
You will then need to reset \parindent to whatever it ought to be (LaTeX default is 20pt): \raggedright drops the value on the floor, so there isn't any way to retrieve it when \raggedright is used outside a group.
///Peter