In general:

If  the dreamer in his dream does the role of a witness, such as an accident, then this dream could highlighting his powers of observation. He has to watch very carefully what is happening around him. The dream, however, could also make the handling of the dreamer with authorities in question.

Psychologically:

Says the dreamer as a witness in, this indicates that he means to be held accountable for his actions or beliefs. Maybe he feels insecure so long until it is accepted by his peers.

Spiritually:

The dreamer recognizes a kind of spiritual legacy in his life, which is a prerequisite for the continuation of his spiritual path.

Traditionally:

Arabian
– To be witness in dream: you must give glory to the truth.

European
– To be in court as witness: no matter how it hires, with one of two people it will destroy itself, because of insignificant incidents will not suffer major depression; Also: we will soon be brought to justice, we should remain extremely vigilant;
– If witness appear in dream against a guilty person: you will be involved in a shameful affair;
– Other testify as witnesses against you: it will be forced to refuse friends a favor.

Hindu
– To be witness in dream: anger and inconvenience.

* See also dream about oath.