On either a Sunday or a Tuesday, burn three green candles over a petition with your friend's name dominating her ex's name. Carry this petition with a High John the Conqueror root in her right pocket during all court proceedings.
I would dress the candles, petition, and root with oils good for court cases, such as Court Case Oil from Lucky Mojo if you aren't really sure. Otherwise, High John the Conqueror root oil will do just fine.
Also, while you do this say a relevant chant or prayer, I suggest Psalms 57.