'... shall be [fined, imprisoned, or both]'

[bwaldon]

Should we treat this as ternary-branching coordination? If so, the first two coordinates are presumably VP... how about "both"?

[nschneid]

Is "both" elliptical for "both fined and imprisoned", and if so, is it a VP with "both" functioning as fused Marker-Head? Or should we just say that it's an NP (fused determiner-head) and anaphora can lead to coordination of unlike categories?

[BrettRey]

Yes, I think both is a fused Marker-Head.

3.2.4 Marker-Head
We have two cases of a phrase in Marker-Head function: The case of etc. (see §5.4.3)
and the case of elliptical stranding of to (see §6.1.1).