This article presents a new
proof of a theorem of Karl Rubin relating values of the Katz p-adic L-function of an
imaginary quadratic field at certain points outside its range of classical interpolation
to the formal group logarithms of rational points on CM elliptic curves. The
approach presented here is based on the p-adic Gross–Zagier type formula proved by
the three authors in previous work. As opposed to the original proof which relied on
a comparison between Heegner points and elliptic units, it only makes use of Heegner
points, and leads to a mild strengthening of Rubin’s original result. A generalization
to the case of modular abelian varieties with complex multiplication is also
included.