At the final presidential debate, when asked what kind of Supreme Court justices they would appoint, Democratic presidential nominee Hillary Clinton and Republican nominee Donald Trump gave different answers.
Clinton insisted that "we need a Supreme Court that will stand up on behalf of women's rights, on behalf of the rights of the LGBT community," adding that "it is important that we not reverse marriage equality, that we not reverse Roe v. Wade."
Trump, meanwhile answered that "I am pro-life and I will be appointing pro-life justices," along with justices that "will be protecting the Second Amendment." He stopped short of saying that he wanted Roe v. Wade overturned.
With the Court closely divided on important cases, the impact of even one Supreme Court justice cannot be overlooked, McConnell emphasized.
For instance, in a 2014 decision, the Supreme Court ruled that the craft chain Hobby Lobby and other "closely-held for-profit" businesses were protected from the federal government's birth control mandate by a religious freedom law, the Religious Freedom Restoration Act.
That was a 5-4 decision with Justice Scalia in the majority, which meant that if just one justice in his place ruled differently, the Green family who owns Hobby Lobby – and other business owners claiming to run their business based on their religious beliefs – would have lost a key religious freedom case.
"The Court is very divided on questions of vital importance to believing and practicing Catholics," said Professor David Upham, attorney-at-law and professor of politics at the University of Dallas.
On one side, four justices have been appointed by Democratic presidents and have ruled consistently together. "They vote in virtual lockstep over 90 percent of the time" and "very rarely file separate opinions," McConnell noted.
They have voted to uphold legal abortion and same-sex marriage and have opposed the religious freedom of Catholics who don't want to cooperate with "the evils of the sexual revolution" like "contraception, abortifacients, and the public celebration of homosexuality," Upham told CNA.
On the other hand, three justices have voted the opposite way on these issues.
They "have repeatedly voted to affirm, and not invalidate state and federal laws designed to secure the right of the child to his life and his parents," Upham said, and "they have voted consistently to affirm and preserve the immunity of Catholics and others against compulsory participation in the practices and celebrations of the sexual revolution."
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And the remaining justice – Justice Anthony Kennedy – "has been less than consistent on these questions," Upham added.
And how closely do the justices on the bench resemble the politics of the president who nominated them to the Court?
Historically, the justices are pretty consistent with the party politics of the president who appointed them, McConnell said. "Presidents don't make mistakes all that often."
"It's certainly true that justices sometimes vote contrary to what you might think are the political leanings of the party who appointed him or her, and that's a good thing," he explained, but added that "it doesn't happen very often."
One example he gave of a justice defying the trend was Justice David Souter – nominated by Republican President George H. W. Bush – who "turned out to be a fairly reliable member of the liberal wing of the court. It's unlikely that that's what President Bush was looking for."
Justices are nominated by the President and confirmed by the Senate. Upham agreed that justices nominated and confirmed by a president and senators all of the same party are more consistent with a President's views.