  A new measurement of $B_{\pi e2}$, the $\pi^+ \to e^+\nu(\gamma)$ decay
branching ratio, is currently under way at the Paul Scherrer Institute. The
present experimental result on $B_{\pi e2}$ constitutes the most accurate test
of lepton universality available. The accuracy, however, still lags behind the
theoretical precision by over an order of magnitude. Thanks to the large
helicity suppression of $\pi_{e2}$ decay, the branching ratio is susceptible to
significant contributions from new physics, making this decay a particularly
suitable subject of study.
