Final answer:
The Supreme Court in Dred Scott v. Sandford ruled that enslaved individuals were not free just by having been in a free territory, so the statement is False. Additionally, the Lecompton Constitution in the Kansas territory represented pro-slavery interests, not the Free Soilers, making that statement also False.
Step-by-step explanation:
The United States Supreme Court case that focused on whether an enslaved person, having lived in free territories, should be free, refers to the Dred Scott v. Sandford decision of 1857. In this landmark case, the Supreme Court ruled that slaves who were taken to free states were not automatically free. Furthermore, the Court declared that black people could not be citizens of the United States, and thus Dred Scott had no standing to sue in federal court. Additionally, the Court said that residence in a free territory did not make a slave free and that Congress had no authority to bar slavery in the territories, striking down the Missouri Compromise.
Regarding the Lecompton Constitution, it was indeed associated with the Kansas territory during the time when Kansas was deciding whether to be a free or slave state. However, the Lecompton Constitution was a pro-slavery document, and its introduction actually showed the influence of pro-slavery elements, not the dominance of the Free Soilers, so the correct answer to whether the Lecompton Constitution showed the dominance of the Free Soilers is False.