In general the following is true about this issue. Social Security will know if you have ever smoked marijuana. If you have ever used marijuana ILLEGALLY there is a good chance it will hurt your case. This is true even if you used it for medicinal purpose. If you have ever smoked marijuana LEGALLY for medicinal purposes there is still a good chance it will hurt your case. If you used it LEGALLY under the guidance of a specialist who is treating you for the condition being tre