Do you have any physical evidence that I trespassed?
The evidence is based on something. What is it based on? This physical evidence. Ha ha! Guilty!
This is a jukugo word that uses the on'yomi readings of the kanji. You just need to remember that 拠 is using the こ reading you learned, not the きょ one. Just remember that you can never trust the word of a 子 (こ), so you always require them to provide physical evidence.