This is not quite the way the question gets raised. The usual focus is on means. But I want to suggest we start with ends.
There are basic questions that should be asked about an end. An end is a goal or result. Nothing ever ends, of course, because life is continuous.
We evolve slowly but surely. Things always change. No end is really the end.
An end is an intention and the first question to ask is will it help or not. The second is will it cause hurt and suffering. The third is will it destroy or kill a person or group.
The intention is vastly more important than the means. If the means are evil -- harm, hurt, lethal force -- they are not justified.
The reason why is that there is no justification for evil.
Does a good end justify evil methods? The answer is no. Ends and means are a unity. Practitioners of evil ends use evil to attain them.
If you say lies and prevarication often obscure evil intent, I agree. That is why Jesus called his enemies hypocrites.
There is never a perfect solution but justifiable solutions begin with rejecting conscious evil and going for what will be the least harmful result.
Ultimately we need to create a world predicated on moving in the direction of the good and avoiding the worst evils of the past.