Theos-Talk Archives (January 2005 Message tt00888)

hostile witness
n. technically an "adverse witness" in a trial who is found by the 
judge to be hostile (adverse) to the position of the party whose 
attorney is questioning the witness, even though the attorney called 
the witness to testify on behalf of his/her client. When the attorney 
calling the witness finds that the answers are contrary to the legal 
position of his/her client or the witness becomes openly 
antagonistic, the attorney may request the judge to declare the 
witness to be "hostile" or "adverse." If the judge declares the 
witness to be hostile (i.e. adverse), the attorney may ask "leading" 
questions which suggest answers or are challenging to the testimony 
just as on cross examination of a witness who has testified for the 
opposition.
See also: adverse witness leading witness 
http://dictionary.law.com/