Depends a little bit on when you destroyed it.
If you destroyed it before it was subpoenaed, then it’s gone forever for both you AND the person requesting it. The only thing that can be used is other copies or other people’s knowledge of the evidence. If you want to say it never existed in the first place, you better be very sure nobody else can refute that.
If, however, there is reasonable belief that you have the materials and/or you destroyed them AFTER subpoena, you can be liable for spoilation of evidence. If the information can be inferred, it will be inferred against the destroyer by spoilation inference rules. Spoilation inference is a legal concept that allows others to conclude that the destruction of evidence took place because the party had consciousness of guilt. Title 18 provides sanctions for intentional destruction of evidence AND helping another party destroy evidence, with penalties including fines and imprisonment up to 20 years, but that’s pretty rarely invoked, the more likely violation is civil procedure rule 37, which can involve dismissal of wrongdoer’s claim, entering a judgement against the wrongdoer in favor of the other party, exclusion of testimony, or adverse inference rules as described above.
ETA: in this case, if the evidence existed as of the date of filing, and was subsequently destroyed, my second paragraph would apply; a reasonable person could conclude that the material would be relevant to the civil case and should thus be preserved.
