Aligning the right parts in multiple \begin{cases}

Question

Is there an intelligent way to left-align the parts right of & of the two cases environments shown below (if x >= 0, otherwise, if y < 0, otherwise). I wonder if there is a better way than using manual spaces:

\begin{align*}
 u(x) &=
  \begin{cases}
   0        & \text{if } x \geq 0 \\
   1        & \text{otherwise}
  \end{cases}
  \\
 \tau &=
  \begin{cases}
   a+b+c+d  & \text{if } y < 0 \\
   1        & \text{otherwise}
  \end{cases}
\end{align*}

Answer 1

You can use the solutions to an earlier question, just exchanging the order of the statements.

Another solution is to use the mathtools package and use something like \mathrlap0\hphantom{a+b+c+d} in place of your 0.