“自作主张”常见的英文表达有 “act on one's own initiative” 、“take the initiative without authorization” 或 “do something without consulting others” 。
act on one's own initiative：强调主动、自发地采取行动，没有事先征得他人同意。例如：He often acts on his own initiative, which sometimes causes trouble.（他经常自作主张，这有时会惹出麻烦 。）
take the initiative without authorization：突出没有得到授权就主动去做某事。例如：She took the initiative without authorization to change the project plan.（她自作主张地更改了项目计划。）
do something without consulting others：更直白地表达没有与他人商量就做事。例如：It's not good to do something without consulting others.（自作主张可不好。）