Assange has appeared in court in London as the U.S. pursues its extradition request, following his arrest at the Ecuadorian Embassy in April.
The U.S. wants the publisher to answer for charges of conspiracy to commit computer intrusion in connection with a leak of classified documents.
Hillgrove declined to comment on the U.S. extradition hearing but said Assange is a journalist who tells the truth at all costs.
Assange was sentenced to 50 weeks in jail in London on Wednesday for breaching his bail by entering the Ecuadorian embassy seven years ago.
