No wonder we've become so assured that surveillance will triumph over evil, that technology will indeed fight injustice for us.

I am normally someone who helps other people fight injustice.

These events made her determined to fight injustice.

He has great skill with unarmed combat styles (especially judo) and uses a variety of devices, mostly of his own devising, to fight injustice.

But he would not mind using unjust method to fight injustice.