One of the pivotal points in translation is the translators success in choosing the appropriate lexis to convey the right and full meaning of the text at hand. Such a success usually outlines the range of freedom granted to the translator to select the right meanings of the lexis to come out with the required meaningful reliable translations. The current study aims at investigating, theoretically and practically, the range of freedom available to translators in making decisive choices between both guided translation and free translation to decide upon the right lexical items and expressions in translating literary and scientific texts. It is worthy to note that although a translator utilizes their knowledge, judgment, experience, and background knowledge to come out with appropriate translations, both genres, i.e. literary and scientific texts with the subjectivity and objectivity that characterize them respectively, put a further burden on the translators shoulder in terms of being either guided or free in the choice of the appropriate lexis to capture the intended meaning fully and come up with an acceptable translation. As such, this study hypothesizes that translators poor knowledge of both lexical meaning and lexical formation can affect the range of lexical item choice in the translation process. It can also break the bond between the lexical items and the things, ideas, and states they represent. The outcome of all this will be mistranslation. One of the key findings of this study is that, in contrast to scientific lexis, where the translator must be objective and guided, literary lexis are free to be translated according to the translators opinions, knowledge, and feelings.