Im not sure about the usage of the "per" preposition, but this translation seems to be pretty straight forward. Is this correct?
If you want to use per, the noun historia needs to be in the accusative case. You can say iudicatus per historiam, but it means "judged through history". There are contexts where that can make sense, but it is not a good translation for "judged by history".
What you want is an agent. The agent is always in the ablative (which for historia is historia but with a long final a). Whether you need a preposition with the agent depends on, well, agency. If it is acting willfully, then you need the preposition a/ab. If the agent is a mere tool, you do not. This is sometimes simplified by saying that human agents take the preposition and others do not, but there is more to it. In this case I would leave the preposition out, but perhaps in some context you could put it in.
If you the thing being judged is an unspecified thing, you need a neuter iudicatum. For an unspecified person the masculine iudicatus is best. The form depends on the number and gender of the judged entity. If it happens to be neuter plural or feminine singular, there is potential for misinterpretation of the participle as an attribute of historia. That can be helped with word order and a preposition. Again, context matters.
I assume you are talking about a general entity. I would invert the word order and say historia iudicatum. Whether this works for you depends on the specific context.