Delaware state policies restrict lawyers from acting as an advocate at a trial in which the lawyer is likely to be a necessary witness, the filing said.
"Christopher J. Clark, having appeared in this matter for Defendant Robert Hunter Biden, hereby moves for leave to withdraw as counsel in the above-captioned matter," the filing said. "Based on recent developments, it appears that the negotiation and drafting of the plea agreement and diversion agreement will be contested, and Mr. Clark is a percipient witness to those issues."
Hunter Biden will continue to receive legal representation from other firms, the filing added.
Biden faces tax evasion and firearms charges, which were set to be resolved by a plea deal and pre-trial diversion agreement. However, the arrangement collapsed and the parties have since reached an impasse in attempting to reach a new deal.
Last week, US Attorney General Merrick Garland announced the appointment of David Weiss as a special counsel tasked with investigating the Hunter Biden case.
The case comes amid investigations by US House of Representatives lawmakers into alleged criminal activity by Joe and Hunter Biden, including bribery and foreign influence peddling.