Employers may not discriminate against employees or applicants who have taken FMLA leave in hiring, promotional decisions, disciplinary actions or other terms and conditions of employment. [29 CFR § 825.220(c); see Bryant v. Dollar General Corp. (6th Cir. 2008) 538 F3d 394, 401–FMLA leave right “would be utterly meaningless if the statute's bar against discrimination failed to prohibit employers from considering an employee's FMLA leave as a negative factor in employment decisions”]

The above quotes are from Cal. Prac. Guide Employment Litigation. So are the following:

5] Prohibited Discrimination: “No covered entity shall discriminate against a qualified individual on the basis of disability in regard to job application procedure, the hiring, advancement, or discharge of employees, employee compensation, job training, and other terms, conditions, and privileges of employment.” [42 USC § 12112(a); 29 CFR §§ 1630.4, 1630.13]
Prima facie case: To establish a prima facie case of discrimination, plaintiff must demonstrate that (i) plaintiff is disabled within the meaning of the ADA; (ii) plaintiff is a qualified individual able to perform the essential functions of the job; and (iii) the employer terminated or refused to rehire plaintiff because of his or her disability. [Nunes v. Wal—Mart Stores, Inc. (9th Cir. 1999) 164 F3d 1243, 1246; Bekker v. Humana Health Plan, Inc. (7th Cir. 2000) 229 F3d 662, 669—670]
a. [9:766] “On the basis of” disability: The ADA prohibits discrimination against an individual “on the basis of” that individual's disability. [42 USC § 12112(a) (emphasis added)]

Cal. Prac. Guide Employment Litigation Ch. 9-A

Improper job standards: Using administrative standards, criteria or methods that discriminate on the basis of disability, or that perpetuate the discrimination by others who are subject to common administrative control. [42 USC § 12112(b)(3)]
Even if the employer does not intend to discriminate, such practices may be unlawful because of their discriminatory impact on persons with disabilities.
• [9:828] An employer's policy of not allowing injured workers to return to work until “100% healed” is a per se ADA violation because it eliminates the required individual assessment whether the worker can perform essential job functions either with or without accommodation. [Hendricks-Robinson v. Excel Corp. (7th Cir. 1998) 154 F3d 685, 699; McGregor v. National R.R. Passenger Corp. (9th Cir. 1999) 187 F3d 1113, 1116]