- Pacific Gas & Electric Co. v. Energy Resources Commission
- Pacific Mutual Life Insurance Co. v. Haslip et al.
- Pacific States Telephone & Telegraph Company v. Oregon
- Packard v. Packard
- Palko v. Connecticut
- Palmore v. Sidoti
- Palsgraf v. Long Island Railroad Company
- Parham v. J. R.
- Paris Adult Theatre v. Slaton District Attorney
- Patterson v. Alabama
- Patterson v. McLean Credit Union
- Patton v. United States
- Paul v. Davis
- Payne v. Tennessee
- Payton v. New York
- Penn Central Transportation Company v. City of New York
- Pennell v. San Jose
- Pennhurst State School & Hospital v. Halderman
- Pennsylvania v. Muniz
- Pennsylvania v. Nelson
- Penry v. Lynaugh
- People v. White
- Perez v. Brownell
- Personnel Administrator v. Feeney
- Philadelphia Newspapers Inc. v. Hepps
- Philadelphia v. New Jersey
- Pierce v. Society of Sisters
- Planned Parenthood of Central Missouri v. Danforth
- Planned Parenthood of Southeastern Pennsylvania v. Casey
- Plessy v. Ferguson
