A supporter of the Army private suspected of supplying classified documents to the WikiLeaks website has refused to testify to a federal grand jury.
He is accusing the US government of using fear tactics to intimidate those who advocate transparent government.
David House is a founding member of the Bradley Manning Support Network.
He invoked his Fifth Amendment rights against self-incrimination after being subpoenaed to the federal courthouse in Alexandria.
Prosecutors have convened a grand jury there to investigate the WikiLeaks disclosures.
Mr House told reporters after his appearance that nearly all the questions posed by prosecutors centred on Bradley Manning.
The private is being held at Fort Leavenworth while military authorities investigate whether he illegally leaked sensitive documents about the Iraq and Afghanistan wars.