A recent paper says no; with more supernovae and a different statistical analysis approach that doesn't treat them all the same finds that the distribution is consistent with a constant expansion. Please follow that last link, and look at the second figure. The blue curve is the dark energy model and the red dashed line is the constant expansion model.
I don't know if this group made any major mistakes--I'm not expert enough on supernovae. But it looks like the foundation for dark energy was worse than I thought. (And I'm not convinced about initial inflation.) "Laws are like sausages, it is better not to see them being made."