In 1810, Benjamin Donahue of Delaware applied to Mr. Barker, mayor of Philadelphia, to assist him in recovering a fugitive, with whose place of residence he was perfectly sure Isaac T. Hopper was acquainted. After a brief correspondence with Friend Hopper, the mayor said to Mr. Donahue, "We had better drop this business, like a hot potato; for Mr. Hopper knows more law in such cases as this, than you and I put together."

He would often resort to the most unexpected expedients. Upon one occasion, a slave case was brought before Judge Rush, brother of Dr. Benjamin Rush. It seemed likely to terminate in favor of the slaveholder; but Friend Hopper thought he observed that the judge wavered a little. He seized that moment to inquire, "Hast thou not recently published a legal opinion, in which it is distinctly stated that thou wouldst never seek to sustain a human law, if thou wert convinced that it conflicted with any law in the Bible?"

"I did publish such a statement," replied Judge Rush; "and I am ready to abide by it; for in all cases, I consider the divine law above the human."

Friend Hopper drew from his pocket a small Bible, which he had brought into court for the express purpose, and read in loud distinct tones the following verses: "Thou shalt not deliver unto his master the servant which is escaped from his master unto thee: He shall dwell with thee, even among you, in that place which he shall choose, in one of thy gates, where it liketh him best: thou shalt not oppress him." Deut. 23: 15, 16.

The slaveholder smiled; supposing, this appeal to old Hebrew law would be considered as little applicable to modern times, as the command to stone a man to death for picking up sticks on the Sabbath. But when the judge asked for the book, read the sentence for himself, seemed impressed by it, and adjourned the decision of the case, he walked out of the court-house muttering, "I believe in my soul the old fool will let him off on that ground." And sure enough, the slave was discharged.

Friend Hopper's quickness in slipping through loop-holes, and dodging round corners, rendered him exceedingly troublesome and provoking to slaveholders. He often kept cases pending in court three or four years, till the claimants were completely wearied out, and ready to settle on any terms. His acute perception of the slightest flaw in a document, or imperfection in evidence, always attracted notice in the courts he attended. Judges and lawyers often remarked to him, "Mr. Hopper, it is a great pity you were not educated for the legal profession. You have such a judicial mind." Mr. William Lewis, an eminent lawyer, offered him every facility for studying the profession. "Come to my office and use my library whenever you please," said he; "or I will obtain a clerkship in the courts for you, if you prefer that. Your mind is peculiarly adapted to legal investigation, and if you would devote yourself to it, you might become a judge before long."

But Friend Hopper could never overcome his scruples about entering on a career of worldly ambition. He thought he had better keep humble, and resist temptations that might lead him out of the plainness and simplicity of the religious Society to which he belonged.

As for the colored people of Philadelphia, they believed in his infallibility, as devout Catholics believe in the Pope. They trusted him, and he trusted them; and it is remarkable in how few instances he found his confidence misplaced. The following anecdote will illustrate the nature of the relation existing between him and that much abused race. Prince Hopkins, a wood-sawyer of Philadelphia, was claimed as a fugitive slave by John Kinsmore of Baltimore. When Friend Hopper went to the magistrate's office to inquire into the affair, he found the poor fellow in tears. He asked for a private interview, and the alderman gave his consent. When they were alone, Prince confessed that he was the slave in question. In the course of his narrative, it appeared that he had been sent into Pennsylvania by his mistress, and had resided there with a relative of hers two years. Friend Hopper told him to dry up his tears, for it was in his power to protect him. When he returned to the office, he informed the magistrate that Prince Hopkins was a free man; having resided in Pennsylvania, with the consent of his mistress, a much longer time than the law required. Mr. Kinsmore was irritated, and demanded that the colored man should be imprisoned till he could obtain legal advice.

"Let him go and finish the wood he was sawing," said Friend Hopper. "I will be responsible for his appearance whenever he is wanted. If the magistrate will give me a commitment, Prince will call at my house after he has finished sawing his wood, and I will send him to jail with it. He can remain there, until the facts I have stated are clearly proved."

The slave-holder and his lawyer seemed to regard this proposition as an insult. They railed at Friend Hopper for his "impertinent interference," and for the absurd idea of trusting "that nigger" under such circumstances.