Duncan E. McKinlay began his career learning the carriage painting trade, gaining practical skills in various locations across the United States. He later pursued a legal education, culminating in his admission to the bar by the Supreme Court of California in 1892. McKinlay commenced his legal practice in Santa Rosa and subsequently held significant roles in the public sector, serving as a second and first assistant United States attorney in San Francisco. His professional journey reflects a transition from skilled craftsmanship to a distinguished career in law and government.

Duncan E. McKinlay's political identity is shaped by a blend of practical experience and legal acumen, suggesting an ideologically agile approach. His career trajectory, from a skilled trade to a legal professional, indicates a unique ability to navigate diverse sectors. McKinlay's governmental roles in San Francisco reveal a calculated engagement with federal law enforcement, hinting at a strategic alignment with regional interests. His rhetorical style likely emphasizes adaptability and localized problem-solving, though the specifics remain intriguingly underexplored.