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We present measurements of the branching fractions for $J/\ensuremath{\psi}\ensuremath{\rightarrow}{e}^{+}{e}^{\ensuremath{-}}$ and ${\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ using 3M $\ensuremath{\psi}(2S)$ decays collected with the CLEO detector operating at the CESR ${e}^{+}{e}^{\ensuremath{-}}$ collider. We obtain $\mathcal{B}(J/\ensuremath{\psi}\ensuremath{\rightarrow}{e}^{+}{e}^{\ensuremath{-}})=(5.945\ifmmode\pm\else\textpm\fi{}0.067\ifmmode\pm\else\textpm\fi{}0.042)%$ and $\mathcal{B}(J/\ensuremath{\psi}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}})=(5.960\ifmmode\pm\else\textpm\fi{}0.065\ifmmode\pm\else\textpm\fi{}0.050)%$, leading to an average of $\mathcal{B}(J/\ensuremath{\psi}\ensuremath{\rightarrow}{\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{\ensuremath{-}})=(5.953\ifmmode\pm\else\textpm\fi{}0.056\ifmmode\pm\else\textpm\fi{}0.042)%$ and a ratio of $\mathcal{B}(J/\ensuremath{\psi}\ensuremath{\rightarrow}{e}^{+}{e}^{\ensuremath{-}})/\mathcal{B}(J/\ensuremath{\psi}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}})=(99.7\ifmmode\pm\else\textpm\fi{}1.2\ifmmode\pm\else\textpm\fi{}0.6)%$, all consistent with, but more precise than, previous …