One reason why a court may require assistance from a foreign court is to obtain evidence from a witness. This evidence may be to answer questions relevant to the determination of an issue of fact, or for
disclosure of documents. Courts usually have the power to
subpoena witnesses only from within the jurisdiction of their own legislature unless they are aided by foreign judicial, or sometimes legislative, authority. For example, Alice in the
United States, could not summon Jean from
France to the US courthouse. Instead, the US court would issue a letter rogatory to a French court, which would then examine Jean in France, and send a
deposition back to the requesting court. Insofar as requests
to US courts are concerned, the use of letters rogatory for requesting the taking of evidence has been replaced in large part by applications under 28 USC 1782, or
Section 1782 Discovery. In many cases, the witness is willing to provide the testimony. However, the target court may compel the testimony of a witness who is unwilling to appear. ==Conventions==