2006 NWT

Many have noticed (and if you hadn't, now you will) that the 2006 edition of the NWT removed the brackets from its translation. The reason why is  as follows (from a letter dated October 14, 2010):

Originally. brackets were included to indicate when an English term could not be linked directly to a corresponding word in the original Hebrew or Greek text, and it was decided that supplementary words had to be included to make the meaning clear in English. However, using supplementary words is a normal procedure when translating text from one language to another because often there is no exact equivalent for some words or expressions. To overcome this problem, translators sometimes need to use two or more words to convey the sense of the original-language word or to make the sentence construction clear in English. Or they may have to add a word to convey an implicit idea that the original-language reader would have understood, even though no specific word appeared in the text. Thus, the added word(s) are necessary because the English text would be incomplete or incorrect without them. Of course, in doing so, translators should not add or remove any information nor distort the meaning when transferring the message from the original language to the target language.

It seems that in the past, some English readers had the impression that the bracketed words indicated where the translators added information, when in fact the words are necessary for good and accurate translation. Therefore, since all the words in brackets are needed to complete the thought exactly as was expressed in the original languages so that the English reader would understand what the original-language reader understood, it was decided to remove brackets from the 2006 printing. (It has always been our standard procedure that when the New World Translation is quoted in our literature. the brackets are never reproduced.) Please note, however, that double brackets have been retained to suggest interpolations (insertions of foreign material) in the original text. - See Luke 23:34 and the Reference Bible footnote.

Most other English Bible translations add words more freely than the New World Translation but do not include brackets to indicate which words had been added in their translations. Readers who desire an understanding of the exact correspondence of the terms found in the English New World Translation with the original-language terms can consult the footnotes in the Reference Bible, The Kingdom Interlinear Translation of the Greek Scriptures, or compare the New World Translation with a Hebrew interlinear Bible.