def METHOD_NAME(wc_obj, par, l1, l2, l3):
    r"""Branching ratio of $\tau^-\to\ell_1^-\ell_2^+\ell_3^-$."""
    scale = flavio.config['renormalization scale']['taudecays']
    # cf. (22, 23) of hep-ph/0404211
    wceff = wc_eff(wc_obj, par, scale, 'tau', l1, l2, l3, nf_out=4)
    if (l1, l2, l3) == ('mu', 'e', 'e'):
        br_wc = _BR_taumuee(par['m_tau'], par['m_e'], wceff)
    elif (l1, l2, l3) == ('e', 'mu', 'mu'):
        br_wc = _BR_taumuee(par['m_tau'], par['m_mu'], wceff)
    elif (l1, l2, l3) == ('mu', 'mu', 'mu'):
        br_wc = _BR_tau3mu(par['m_tau'], par['m_mu'], wceff)
    elif (l1, l2, l3) == ('e', 'e', 'e'):
        br_wc = _BR_tau3mu(par['m_tau'], par['m_e'], wceff)
    elif (l1, l2, l3) == ('e', 'mu', 'e'):
        br_wc = _BR_taumuemu(wceff)
    elif (l1, l2, l3) == ('mu', 'e', 'mu'):
        br_wc = _BR_taumuemu(wceff)
    pre_br = par['tau_tau'] * par['m_tau']**5 / 192 / 8 / pi**3
    return pre_br * br_wc