To summarize the comments I had made under the question, the use of an elliptical construction for list items can be ambiguous.
Had I not read this question, I would not have interpreted the following phrase as elliptical:
involuntary commitment, drugging, and ECT treatments
Instead, I would have considered involuntary as applying only to the first list item.
In order to make it explicit, you can repeat involuntary:
involuntary commitment, involuntary drugging, and involuntary treatments
But if you don't like that repetition, you need to find other ways of constructing the sentence that make the ellipsis clear.
For instance:
These things were involuntary: commitment, drugging, and ECT treatment.
A further comment added more context to the phrase:
the legalities and inherent assumptions that serve as the basis for involuntary: commitment, drugging, and ECT treatments
However, that use of a colon would not normally be considered correct. When you use a colon, it's generally thought that the sentence should sound grammatical if it were replaced with a period and the sentence ended there.
In other words, when considering the appropriateness of the colon, we would look at this:
✘ . . . the legalities and inherent assumptions that serve as the basis for involuntary.
But the following would be okay (assuming, of course, the existence of the right words at the start of the sentence):
✔ (Consider) the legalities and inherent assumptions that serve as the basis for involuntary actions: commitment, drugging, and ECT treatments.
But while this sentence is syntactically correct, it is still semantically ambiguous because the list items could be taken to apply to the legalities and inherent assumptions rather than to involuntary actions.
Note that in vertical lists, because of the nature of their presentation, the rule for what precedes a colon is sometimes relaxed:
the legalities and inherent assumptions that serve as the basis for involuntary:
- commitment
- drugging
- ECT treatments
Given this visual presentation, the intended meaning is more clear.
But whether or not this is actually acceptable—as well as how to punctuate the list items—depends on the particular style guide being followed, if any.
Another possibility when it comes to phrasing is the following:
the legalities and inherent assumptions that serve as the basis for involuntary actions such as commitment, drugging, and ECT treatments
Or, if you don't want to add something like actions, you might be able to use a numbered horizontal list:
the legalities and inherent assumptions that serve as the basis for involuntary (1) commitment, (2) drugging, and (3) ECT treatments
