We present a nonparametric method to determine the sign of w + 1 in the equation of state of dark energy .
It is based on geometrical behaviour and is more tolerant to uncertainties of other cosmological parameters than fitting methods .
It permits to distinguish between different classes of dark energy models even with relatively low precision data .
We apply this method to SNLS supernovae and to gold sample of re-analyzed supernovae data from Riess et al . 2004 [ 1 ] .
Both data sets show strong indication of w < -1 .
If this result is confirmed by more extended and precise data available in near future , many of dark energy models , including simple cosmological constant , standard quintessence models without interaction between quintessence scalar field ( s ) and matter , and scaling models are ruled out .