Keep live crabs on ice until ready to can. Wash thoroughly in several changes of cold water.
Simmer crabs 20 minutes in water containing 1/4 cup lemon juice and 2 tablespoons salt per gallon. Cool in cold water, drain, remove the back shell, and remove meat from the body and claws.
Soak the meat for 2 minutes in cold water containing 2 cups lemon juice or 4 cups white vinegar plus 2 tablespoons salt per gallon. Drain and squeeze out excess moisture.
Pack 6 ounces of crab meat in each half-pint jar or 12 ounces in each pint jar, leaving 1-inch headspace.
Add 1/2 teaspoon citric acid or 2 tablespoons lemon juice to each half-pint; add 1 teaspoon citric acid or 4 tablespoons lemon juice to each pint. Add hot water, maintaining 1-inch headspace.
Pressure process half-pints for 70 minutes and pints for 80 minutes.
Dial gauge: 11/12/13/14 psi at 0–2,000/2,001–4,000/4,001–6,000/6,001–8,000 ft. Weighted gauge: 10 psi through 1,000 ft and 15 psi above 1,000 ft.