A means can be justified only by its end. But the end in its turn needs to be justified.

If the end does not justify the means - what can?

You think the end justifies the means, however vile. I tell you: the end is the means by which you achieve it. Today's step is tomorrow's life. Great ends cannot be attained by base means. You've proved that in all your social upheavals. The meanness and inhumanity of the means make you mean and inhuman and make the end unattainable.

If the end doesn't justify the means, what does? (Robert Moses)

The end justifies the means. But what if there never is an end? All we have is means.

The principle that the end justifies the means is in individualist ethics regarded as the denial of all morals. In collectivist ethics it becomes necessarily the supreme rule.

The end cannot justify the means, for the simple and obvious reason that the means employed determine the nature of the ends produced.

He who wills the end wills the means also,

He who wills the end, wills the means also, and the means must involve some risks, and even some losses.

No axiom is more clearly established in law or in reason than wherever the end is required, the means are authorized; wherever a general power to do a thing is given, every particular power for doing it is included.

The result justifies the deed
(Exitus acta probat)

Anything can become excusable when seen from the standpoint of the result

Can you justify your existence then?

...[M]an and generally any rational being exists as an end in himself, not merely as a means to be arbitrarily used by this or that will, but in all his actions, whether they concern himself or other rational beings, must always be regarded at the same time as an end... [R]ational beings... are called persons, because their very nature points them out as ends in themselves, that is, as something which must not be used merely as means, and so far therefore restricts freedom of action (and is an object of respect).