A subpoena to testify is a court order. To disregard a court order you can be charged with contempt of court. Understand that these subpoenas are auto generated for all cases that are charged and therefore the case against your boyfriend may still be dismissed after everything you have done.
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Mr. Leone made a very important point, the State Attorney's Office determines whether criminal charges are dropped, not the victim or witnesses. While this is true in all criminal cases, domestic violence prosecutors seem to take this situation even more seriously presumably given the nature of domestic violence and the unique relationship between the alleged victim and defendant.
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