  We study the All-Line Transverse (ALT) shift which we developed for on-shell
recursion of amplitudes for particles of any mass. We discuss the validity of
the shift for general theories of spin $\leq$ 1, and illustrate the connection
between Ward identity and constructibility for massive spin-1 amplitude under
the ALT shift. We apply the shift to the electroweak theory, and various
four-point scattering amplitudes among electroweak gauge bosons and fermions
are constructed. We show explicitly that the four-point gauge boson contact
terms in massive electroweak theory automatically arise after recursive
construction, independent of UV completion, and they automatically cancel the
terms growing as (energy)$^4$ at high energy. We explore UV completion of the
electroweak theory that cancels the remaining (energy)$^2$ terms and impose
unitarity requirements to constrain additional couplings. The ALT shift
framework allows consistent treatment in dealing with contact term ambiguities
for renormalizable massive and massless theories, which we show can be useful
in studying real-world amplitudes with massive spinors.
