With regards to the gloves:
One dark leather glove was found at the crime scene, its match found near Kato Kaelin's guest house behind Simpson's Rockingham Drive estate.[10] Kaelin testified that he had heard "thumps in the night" in the same area around the guest house the night of the murder.[10] Brown had bought Simpson two pairs of this type of glove in 1990.[10] Both gloves, according to the prosecution, contained DNA evidence from Simpson, Brown and Goldman, with the glove at Simpson's house also containing a long strand of blonde hair similar to Brown's.[10]
On June 15, 1995, defense attorney Johnnie Cochran goaded assistant prosecutor Christopher Darden into asking Simpson to put on the leather glove that was found at the scene of the crime. The prosecution had earlier decided against asking Simpson to try on the gloves because the glove had been soaked in blood (according to prosecutors) from Simpson, Brown and Goldman,[15] and frozen and unfrozen several times. Darden was advised by Clark and other prosecutors not to ask Simpson to try on the glove,[
citation needed] but to argue through experts that in better condition, the glove would fit. Instead, Darden decided to have Simpson try on the glove.
The leather glove seemed too tight for Simpson to put on easily, especially over the latex gloves he wore underneath.[10] Uelmen came up with and Cochran repeated a quip he had used several times in relation to other points in his closing arguments, "If it doesn't fit, you must acquit." On June 22, 1995, assistant prosecutor Christopher Darden told Judge Lance Ito of his concerns that Simpson "has arthritis and we looked at the medication he takes and some of it is anti-inflammatory and we are told he has not taken the stuff for a day and it caused swelling in the joints and inflammation in his hands." The prosecution also stated their belief that the glove shrank from having been soaked in blood and later testing.[10] A photo was presented during the trial showing Simpson wearing the same type of glove that was found at the crime scene.
https://www.quora.com/Assuming-O-J-was-guilty-why-did-the-gloves-not-fit-Whats-the-argument-against-Johnny-Cochrans-famous-argument-If-the-gloves-dont-fit-you-must-acquit