In legal shorthand, the plaintiff is written as the Greek letter pi (π) and the defendant as the Greek letter delta (Δ). These are the standard symbols for plaintiff and defendant that lawyers, judges, and law students have used for decades in handwritten notes, case briefs, and internal memos. When Greek characters aren’t practical, “P” and “D” do the same work.
Why Pi and Delta
Pi stands in for plaintiff because it shares the opening sound. Delta does the same for defendant. The shapes matter as much as the sounds: π reads as two vertical legs under a bar, Δ as a triangle, and that visual contrast lets you tell the parties apart at a glance on a crowded page.
There’s no statute or ancient tradition behind the convention. It caught on because legal work means writing party names over and over, and two quick Greek letters are faster than spelling anything out. Most law students pick the habit up during their first semester of case briefing, and it tends to stick.
How To Type Pi and Delta
Getting these symbols into a digital document takes about two seconds once you know the shortcut.
- Pi (π) on Windows: hold Alt and type 227 on the numeric keypad, then release Alt.
- Pi (π) on Mac: press Option + P.
- Delta (Δ) on Windows: hold Alt and type 30 on the numeric keypad, then release Alt.
- Delta (Δ) on Mac: press Option + J.
If you use these symbols often in Microsoft Word, set up AutoCorrect. Open File, then Options, then Proofing, then AutoCorrect Options. Type a short trigger like “pltf” in the Replace field and paste π into the With field. Word will swap the trigger for the symbol every time you type it. The same trick works for Δ.
On an iPhone or iPad, copy the symbol, open Settings, then General, then Keyboard, then Text Replacement. Paste the symbol into Phrase and assign a shortcut like “ddef” in the Shortcut field. Android devices offer the same thing through the personal dictionary in keyboard settings.
When To Use P and D Instead
Not every platform renders Greek characters cleanly. Email clients, older case management systems, and some court e-filing portals turn special characters into question marks or empty boxes. When that’s a risk, practitioners fall back on plain letters: “P” for plaintiff and “D” for defendant. Longer internal memos sometimes use “Plf” and “Def” instead, because a lone “D” can be ambiguous when the same document also references courts or document numbers.
Keep this informal shorthand separate from formal citation abbreviations. The Bluebook and similar manuals govern how to shorten party names in briefs and law review footnotes, and those rules address a different audience: published work that other lawyers will rely on. Shorthand is for your own speed. Citation abbreviations are for the record.
Symbols for Petitioner, Respondent, and Criminal Parties
Plaintiffs and defendants aren’t the only parties with Greek-letter stand-ins. In appellate and administrative matters, practitioners use psi (Ψ) for the petitioner and theta (Θ) for the respondent. The logic matches π and Δ: each symbol shares an opening sound with the role it represents.
Criminal cases don’t follow the same pattern. The prosecution appears as “the State,” “the People,” or “the United States,” and no single Greek symbol has taken hold for any of them. Most practitioners write “S” or “Gov” and move on.
Where This Shorthand Does Not Belong
Symbols belong in speed-driven contexts: case briefs, handwritten deposition notes, internal memos, research summaries for a supervising attorney. Anywhere the audience already knows the convention and the document stays in-house, shorthand saves real time.
Formal court filings are a different matter. Federal Rule of Civil Procedure 10 requires every complaint to include a caption listing the names of all parties, and later pleadings must name at least the first party on each side.1Legal Information Institute. Federal Rules of Civil Procedure Rule 10 – Form of Pleadings State courts impose similar requirements. A motion that identifies someone as “π” instead of a full name is likely to be rejected by the clerk, and even if accepted, it invites docket confusion. Judgments, orders, and anything else that becomes part of the public record should use full party names.
Accessibility is the other limit. Screen readers like JAWS and NVDA typically announce π as “pi” and Δ as “delta,” which doesn’t help a listener who doesn’t already know what the letters mean in legal context. Federal guidance under Section 508 advises against special characters in public-facing content because assistive technology handles them inconsistently.2Section508.gov. Social Media For anything with a broad audience or an accessibility requirement, spell out “Plaintiff” and “Defendant.”
A reasonable rule of thumb: use the symbols freely in your own notes, and switch to full words or alphanumeric abbreviations when the document will travel beyond your team.