Question: who plays jack mccoy on law & order
[{'answer': 'Samuel Atkinson Waterston', 'provenance': [{'wikipedia_id': '168518', 'title': 'Sam Waterston', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 25, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '168518', 'title': 'Sam Waterston', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 797, 'bleu_score': 0.926765503154635, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 4775603428236819704}, 'section': 'Section::::Abstract.'}]}]