In the District of Delaware, the district court judges often refer substantive issues to the magistrate judges, even absent consent of the parties. This is one way that the judges manage the incredible load of the patent docket here.
When dealing with substantive referrals (not referrals for mediation/ADR), the Court uses an assignment system, where particular district court judges tend to refer cases and motions only to their assigned magistrate judges (with occasional exceptions).
The most recent announcement of magistrate judge assignments that I know of was made at a Federal Bar Association lunch back in September 2019:
- Magistrate Judges Thynge …