Back in 2000, Jonathan Schaffer, who is Distinguished Professor of Philosophy at Rutgers, The State University of New Jersey, US, published the first paper to examine the concept of ‘Trumping Preemption’ in: The Journal of Philosophy, Vol. 97, No. 4, Special Issue: Causation. (Apr., 2000), pp. 165-181.
“Imagine that it is a law of magic that the first spell cast on a given day match the enchantment that midnight. Suppose that at noon Merlin casts a spell (the first that day) to turn the prince into a frog, that at 6:OOpm Morgana casts a spell (the only other that day) to turn the prince into a frog, and that at midnight the prince becomes a frog. Clearly, Merlin’s spell (the first that day) is a cause of the prince’s becoming a frog and Morgana’s is not, because the laws say that the first spells are the consequential ones.”
The idea of Trumping Preemption has now received further consideration in a 2015 paper for the journal Acta Analytica. Its author, Sara J. Bernstein, who is Thomas J. and Robert T. Rolfs Associate Professor of Philosophy at the University of Notre Dame. takes ‘A Closer Look at Trumping’ in: Acta Analytica, March 2015, Volume 30, Issue 1, pp. 41-57.
“According to Schaffer (2000a), ‘trumping preemption’ is a category of redundant causation distinct from early and late preemption and from overdetermination. I show that the putative causal difference between causal processes in cases thought to be trumping preemption generates early preemption or overdetermination rather than trumping.”
BONUS etymology: Trump
Trump (verb)  “fabricate, devise,” 1690s, from trump “deceive, cheat” (1510s), from Middle English trumpen (late 14c.), from Old French tromper “to deceive,” of uncertain origin. And:
Trump (verb)  “surpass, beat,” 1580s. Also:
Trump (verb)  “to break wind,” colloquial, UK. Orig. unk., prob. onomatopoeic.