SCOTUS Alignment

The Martin-Quinn score is the standard quantitative measure of Supreme Court justice ideology: higher = more conservative, lower = more liberal, calibrated on the actual voting record of every justice since 1937. We average the court median M-Q score over each president’s term, count how many justices they appointed, and compute the share of the term during which the court median matched the president’s party.

Court-median matches president’s party when either (a) the median is positive (conservative) and the president is Republican, or (b) the median is negative (liberal) and the president is Democrat. Terms with no M-Q coverage (pre-1937, post-2023) are excluded from match-rate calculations.

Each row is one presidential term. Avg court median is the Martin-Quinn ideology of the median justice, averaged across each year of the term. Positive = conservative lean, negative = liberal lean. Match % is the share of the term during which the court median aligned with the president’s party.

Not every appointment ages the same way. This table ranks every president who placed a justice on the Supreme Court by (a) how many they placed and (b) the average lifetime Martin-Quinn score of those appointees over their full tenure — which captures ideological drift. Eisenhower and Nixon notoriously appointed justices who drifted leftward (Warren, Blackmun); Reagan and Trump I appointees have stayed close to their appointment-day ideology.

Donald J. Trump’s second term began 2025 and runs through 2029. Appointments so far: 0. The Martin-Quinn dataset’s latest release covers through SCOTUS term 2023, so avg court median / match-% readings are unavailable for terms starting after that point until the next release lands.

Updates nightly — the appointment count refreshes when confirmation votes are logged. Court-median readings will refresh automatically after the next Martin-Quinn annual release (typically spring, one term behind).

Martin-Quinn scores. Developed by Andrew Martin and Kevin Quinn (2002), M-Q scores are IRT-model-derived justice ideology estimates calibrated on every merits vote at the Supreme Court since 1937. The court median is the M-Q score of the 5th-ranked justice (out of 9), which determines the outcome of close cases. Higher = more conservative. Updated annually at mqscores.wustl.edu.

Match rule. A term’s court median matches the president’s party when (a) median > 0 and president is Republican, or (b) median < 0 and president is Democrat. same_party_majority_pct is the share of the term during which this condition held.

Appointment count. From the Federal Judicial Center biographical directory — the official US-government justice registry. Count includes only confirmed appointments (not nominations).

Appointment legacy. avg_lifetime_med is the mean Martin-Quinn score of each of a president’s appointees averaged across their entire tenure on the Court (not just the day they were seated). Captures the well-known drift pattern (Eisenhower / Nixon → leftward) and the modern conservative-hold pattern (Reagan onward → stable).

Coverage.

• Martin-Quinn: 1937 – 2023 term. Pre-1937 terms excluded from ideology metrics.
• Appointment counts: full history available since Washington.
• Post-2023 terms (Biden last year, Trump II) have null M-Q entries pending next M-Q release.

Caveats.

• Match % is a crude binary summary. A president with a +0.05 court median (barely conservative) and a president with a +2.5 court median (Alito-tier conservative) both get 100% match credit against a GOP incumbent. The avg_court_median column preserves magnitude.
• Only three Supreme Court “realignments” have happened since 1937: FDR’s court-packing fight (1937), the Warren Court (1953-1969), and the Trump I majority (2017-2020).
• Appointment timing is substantially random — vacancies depend on death + retirement — so a president’s appointment count may not reflect their ideological intent.

Source. Martin-Quinn 2024 release (mqscores.wustl.edu) · Federal Judicial Center biographical directory · Presidential party proxy: PARTY_BINARY (D=-1, R=+1).

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