When Barry Peters was an in-house benefits lawyer for Bell Atlantic Corp.(now Verizon Communications Inc.), he took a legal drafting seminar taught by a professional writer. “There were a number of very helpful suggestions,” he recalls.

Unfortunately, one of the writing tips–avoid placing a phrase at the end of a long, compound sentence that modifies a thought near the beginning of the sentence–contributed to a $1.67-billion error in a retirement plan document Peters drafted for Bell Atlantic.