He entered private practice in St. Louis, Missouri, where he was joined in 1899 by his brother, future Senator Xenophon P.

With no obligation to follow the strictures of the constitution or local law, there were many complaints by American expatriates, especially one by Lorrin Andrews, former Attorney General of the Territory of Hawaii, who charged that Wilfley had voided a will by a person leaving some of his money to the Catholic Church because of his prejudice against it.

In two weeks half a hundred women had voluntarily enrolled themselves as former residents of Shanghai...It was an exodus, a hegira...If there is an American girl in any disorderly house, Wilfley and his district attorney do not know of it.

"[4] On February 20, 1908, United States Representative George E. Waldo introduced articles of impeachment against Wilfley and the resolution was referred to the House Judiciary Committee.

He wrote a letter to his Secretary of State, Elihu Root, where he stated..."It is clear that Judge Wilfley has been attacked not because he has done evil, but because he has done good.....If the attack were to succeed the beneficiaries would be every keeper of a house of prostitution, every swindling lawyer, every man who lives by blackmailing corruption in the cities of the Far East.” The minority leader in the House of Representatives, John Sharp Williams, a Democrat, called for an investigation of Roosevelt, asserting that he was interfering with the Congressional investigation.

[8] Despite O'Shea's conviction, the situation was so poisoned, Wilfley resigned at the end of 1908 and returned to the U.S. for good.

As a result of Wilfley's investigations, the Mexican government under President Francisco Madero agreed to pay an indemnity of 3,100,000 pesos to the Republic of China for the massacre.