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This analysis of the electroclinic effect in ferroelectric liquid crystalswith a first order Smectic-$A^*$--Smectic-$C^*$ (Sm-$A^*$--Sm-$C^*$)transition, shows they can be either Type I or Type II. In temperature--fieldparameter space Type I systems exhibit a macroscopically achiral (in which theSm-$C^*$ helical superstructure is expelled) low-tilt (LT) Sm-$C$--high-tilt(HT) Sm-$C$ critical point, which terminates a LT Sm-$C$--HT Sm-$C$ first orderboundary. This boundary extends to an achiral-chiral triple point where theachiral LT Sm-$C$ and HT Sm-$C$ phases coexist with the chiral Sm-$C^*$ phase.In Type II systems the critical point, triple point, and first order boundaryare replaced by a Sm-$C^*$ region, between LT and HT achiral Sm-$C$ phases, atlow and high fields respectively. When the field is ramped up, the Type IIsystem displays a reentrant Sm-$C$--Sm-$C^*$-Sm-$C$ phase sequence. Adiscontinuity in the tilt of the optical axis at each of the two phasetransitions means the Type II system is tristable. The system is Type I or TypeII depending on the ratio of two length scales, one is the zero-field Sm-$C^*$helical pitch, the other depends on the latent heat at the zero-field firstorder Sm-$A^*$--Sm-$C^*$ transition. A system could be experimentally tuned byvarying enantiomeric excess, between Type I and Type II behavior. We also showthis Type I vs Type II behavior is the Ising universality class analog of TypeI vs Type II behavior in XY universality class systems. Lastly, we make acomplete mapping of the phase boundaries in temperature--field--enantiomericexcess parameter space (not just near the critical point) which shows a varietyof interesting features, including a multicritical point, tricritical pointsand a doubly reentrant Sm-$C$--Sm-$C^*$-Sm-$C$--Sm-$C^*$ phase sequence.

A New Twist on the Electroclinic Critical Point: Type I and Type II Smectic $C^*$ Systems