I kept asking for anything authoritative and all I see is people back and forth stuck in the issues. I found this from Stanford University on why the principle of double-effect applies.
It would be wrong to throw someone into the path of a runaway trolley in order to stop it and keep it from hitting five people on the track ahead; that would involve intending harm to the one as a means of saving the five. But it would be permissible to divert a runaway trolley onto a track holding one and away from a track holding five: in that case one foresees the death of the one as a side effect of saving the five but one does not intend it.
Two thoughts: first, whereas Stanford University might speak authoritatively on
philosophy, it does not speak authoritatively on
Catholic moral theology. The fact that somewhere outside the teaching of the Church makes a claim, does not make that claim true. Sorry (but nice try.

).
Second, you misquote the document in a way to make it seem that it is saying that the trolley example is one that demonstrates double effect. That’s misleading. Rather, the article merely states that:
Many morally reflective people have been persuaded that something along the lines of double effect must be correct. No doubt this is because at least some of the examples cited as illustrations of DE have considerable intuitive appeal.
“Many morally reflective people” think that? Hmm… doesn’t sound like it proves your case, nor that it says that this is what the Church teaches.
“At least some of the examples cited”… but not all? You mean that it’s possible to mis-use double effect? Really? C’mon…
The examples “have considerable intuitive appeal”? That’s it? Not even that the author, here, is claiming that they work – just that they have appeal…?!?
To suggest that this quotation demonstrates an ‘authoritative’ position – by Stanford University no less (appeal to authority, much?) – is misleading. I hope that wasn’t your intent…