If a divorce decree states you can ask for your ex-spouses Tax Documents in Good Faith, what does that include?

You are allowed to verify his income, to insure he is paying his fair share.

You get to see them to show in court he should be paying more in Child Support. You get a W2, any 1099s, and copies of his state and federal returns.

How do I go about obtaining them when he refuses my requests in email and on the phone?

You go to court and get an order from the judge, then have it served on him. If he still refuses you go back to court and they can sanction him, they may attach his assets.

There are usually Child Support enforcement offices in every jurisdiction to help you get your child’s due. Look for them or ask at your local Family Law court.

go to court, let the judge issue an order, have him served, then he can produce them or go to jial for contempt of a court order.