Slaughtering consists of cutting the trachea and esophagus; for definitions of their vertical extents see 20:1-2 and 24:12-14. They must be cut before the spine is cut (20:3-4) and the majority of the spine should not be cut (24:5). They must not become detached from the neck before being cut (24:15-20). In an animal it is sufficient to cut through most of each of them; in a bird, most of either of them (21:1, and see 2-5). They should be examined immediately after slaughtering to verify that they were cut properly (25:1-3).
The cutting must be done without pausing (even momentarily: 23:2) at any stage (23:5-6); by slicing rather than pressing or chopping (24:1,6); and from front to back, with the cutting instrument not hidden (24:7-11). The cutting must be done by direct action of the slaughterer; it is then valid even if there was no intent to slaughter (3:1;7:1). On other laws involving the intent of the slaughterer see 4:1-7;5:1-3;11:3-4;12:1-2.
Slaughtering may be done with any instrument whose cutting edges are strong and entirely smooth (6:1) and are long enough to cut without excessive pressure (8:1, and see 6:4;18:7;24:2-4). The instrument must be free of blemishes on or close to its cutting edges that can “catch” even an object as thin as a hair (18:2, and see 18:4-6,10). It should be checked (by touch) for such blemishes both before and after slaughtering with it (18:3,9,11-12); this checking must be done very carefully by a qualified expert (18:17). If a blemish is found after slaughter the slaughter is invalid even though no blemish was present before slaughter (18:1; see 18:11, 13,15-16). On other laws relating to the instrument see 6:2-3;9:1;10:1; 18:8,14.
It is customary not to allow a person to slaughter unless he is an observant Jew (see 2:1-2ff) and a qualified scholar has certified that he knows the relevant laws (see 18:17;23:1;25:1), and it is customary that women not be slaughterers (1:1-2). On slaughtering by children and other special classes of persons see 1:5-9;2:1-9,11;11:1; on slaughtering by two people see 2:10;24:4. On the trustworthiness of slaughterers see 1:1,3,12-14;2:2;18:18-20;64:21;119:16-18. The slaughterer first recites the blessing “…Who commanded us about slaughtering” (19:1); on laws relating to the blessing see 1:10 and 19:2-8.
Shulchan Aruch, Copyright (c) 1999 Project Genesis, Inc.