Sentence:  It was the first time I'd told Collier what I knew, but it didn't seem to worry him at all. He'd had too many years of being a <WSD>law unto himself</WSD>, and he took it in his stride. 
Meaning of the word marked with <WSD> tags:  One who flouts the law or conventional wisdom; one who ignores rules or logic to behave according to his or her own standards.