See also the Dispute response object.

availability

Managing disputes via the API is only available to merchants who can access disputes in the Braintree Control Panel.

If you want to look up a single dispute using its ID, use the find method.

Node.js 
gateway.dispute.find("a_dispute_id").then(dispute => { });

If the dispute can't be found, it will return a notFoundError.

Arguments
disputeId required, String

The unique dispute identifier.