“Douglas accepted Dred Scott, and in Dred Scott, the Chief Justice had said that the right to own slaves is expressly affirmed in the Constitution. And Lincoln said in the debates that it was implied but not expressly affirmed. The argument against any restriction on slavery was that any right expressly affirmed in the Constitution takes precedent over any law or regulation in any jurisdiction whatever. (Remember, the supremacy clause in Article VI of the Constitution says that this Constitution, and the laws and treaties made in pursuance thereof, are the supreme law of land—anything in any law or a constitution of any state to the contrary not withstanding.)”

2000s, The Real Abraham Lincoln: A Debate (2002), The Lincoln-Douglas Debates

1860s, Cooper Union speech (1860)

1850s, The House Divided speech (1858)

2000s, The Real Abraham Lincoln: A Debate (2002), The Right of Secession Is Not the Right of Revolution

2000s, The Real Abraham Lincoln: A Debate (2002), Q&A
Context: DiLorenzo thinks that it is a reflection on Lincoln's anti-slavery character that he supported the Fugitive Slave Act. But the Fugitive Slave Clause is in the Constitution, and Lincoln thought that any refusal to implement the right clearly defined in the Constitution would justify secession. You can't pick and choose which parts of the Constitution you like. Once you do that, then the Constitution is simply, as Jefferson said once, "a blank sheet of paper." Jefferson said that when he was contemplating purchasing Louisiana. And having said that by purchasing it he would make the Constitution a blank sheet of paper, he went ahead and purchased Louisiana.

1850s, The Present Aspect of the Slavery Question (1859)
Context: Our fathers, therefore, were fully alive to the scope of their words and their work; and thus, as I believe, the Constitution of the United States, in its essential spirit and intention, recognizes the essential manhood of Dred Scott as absolutely as it does that of the President, of the Chief Justice, or of any Senator of the United States. I think I have not unfairly stated the spirit of the age, the sentiments of the fathers, and the original doctrine of this government upon the question of slavery. The system was recognized by law, but it was considered an evil which Time was surely removing. And, as if to put this question at rest forever, to show that the framers of this government did not look forward to a continuance of slavery, Mr. Stephens of Georgia, the most sagacious of the living slavery leaders, says, in June of this year, 'The leading public men of the South, in our early history, were almost all against it. Jefferson was against it. This I freely admit, when the authority of their names is cited. It was a question which they did not, and perhaps could not, thoroughly understand at that time'.

1850s, The House Divided speech (1858)

As quoted in His Brother's Blood: Speeches and Writings, 1838–64 https://books.google.com/books?id=qMEv8DNXVbIC&pg=PA193&lpg=PA199 (2004), edited by William Frederick Moore and Jane Ann Moore, p. 199
1860s, Speech to the U.S. House of Representatives (April 1860)

2000s, The Real Abraham Lincoln: A Debate (2002), The Lincoln-Douglas Debates