The Supreme Court in its conference tomorrow will review the petition for writ of certiorari in Lucia v. SEC. The question presented is whether administrative law judges of the SEC are considered to be employees or officers of the United States under the Appointments Clause.
I believe the USPTO encountered a similar issue a few years ago.
You can read the petition here: [Link].
Update 1/12/2018:
The Supreme Court granted the petition for certiorari in this case today.