The legal and ethical merits of a company allegedly having a zero-tolerance policy, but not giving it to an employee in writing. What legal issues does this present?

Research the Internet and University Library for information on medical marijuana laws and drug testing in the workplace
Discuss the case scenario in a written report and all its applicable topics being sure to include the following:  
Q1 – Whether or not the woman has a valid claim. Support your position using laws or statutes, including any legal cases on the matter.
Q2 – Whether or not the company has a valid defense. Support your position using law or statutes, including any legal cases on the matter.
Q3 – The legal and ethical merits of a company allegedly having a zero-tolerance policy, but not giving it to an employee in writing. What legal issues does this present?
Q4 – The significance of an employee handbook and whether or not it can be construed as a legal contract between employer and employee.
Q5 – Whether or not the employment-at-will doctrine takes precedence despite other laws in effect.
Q6 –  Recommend and describe a conflict resolution process as a solution to handle the matter, hoping to avoid a lawsuit.
 ~ Cite a minimum of two federal laws and one state law, in addition to other sources required for this assignment that apply to this case scenario being sure to cite them correctly in the body of your paper as well as the References page.
Write a 1,750- to 2,100-word report in the third person voice, exclusive of the policy.
Use headings to appropriately signal the topics and keep your document organized.
Use a minimum of five in-text citation sources within your paper and identify them in your APA correctly formatted References page.