The National Institute of Justice (NIJ) worked with the Police Scientific Development Branch (PSDB) of the Home Office in the U.K., where they have a strong program in the stab area. The PSDB looked at the dynamics of the act of stabbing and developed an "instrumental" knife blade that could measure the thrust and energy of a stab. The PSDB determined that, for the highest level of protection, a stab-resistant vest should be able to withstand 43 joules of energy, allowing no more than 7 millimeters of penetration. The PSDB issued a stab-resistance standard in 1999 for vests to be worn by law enforcement officers. The NIJ Standard relies heavily on PSDB's research, but also has input from the National Armor Advisory Board and the Law Enforcement and Corrections Technology Advisory Council. NIJ Standard 0115.00: Stab Resistance of Personal Body Armor, published in September 2000, puts stab-resistant tests into two categories, each describing the kind of threat a garment is designed to stop. The article includes sources for further information on development of the NIJ standard as well as how to obtain a copy of the standard.