Regardless of industry, almost all businesses with employees have some form of a dress code policy. When creating a dress code policy for your business, apply your policy equally to all employees. Unfair dress code policies are considered discriminatory and can be grounds for a lawsuit.
A Report on Temporary Help, On-Call, Direct-Hire Temporary, Leased, Contract Company, and Independent Contractor Employment in the United States
Besides not defining the term "employee", most statutes fail to spell out who the employer is. There is potential ambiguity on this issue when businesses use temporary agency, leased, or contract workers. Although the primary employer is generally the temporary help, leasing, or contract company, the client may be regarded as a “joint employer” under some laws.
The U.S. Equal Employment Opportunity Commission recently held a meeting with "a battery of experts" on disparate treatment in hiring. According to the EEOC, hiring discrimination continues to run rampant.
Time for a grain of salt here: According to the EEOC's press release, most of the experts were from the EEOC, or were individuals who had been denied jobs and claimed they were discriminated against.
Generally, an employer has the right to expect that certain guidelines involving dress and grooming be met in the workplace, and can set forth policies regarding these issues.
Plaintiff's lawyer Donna Ballman and The Evil HR Lady have had good posts recently on common employee misconceptions about employment law, including the "right" to see what is in one's personnel file and the "right" to take a break.*
*Depending on where the employee lives, he may have these rights, but in many states he does not. And the federal Fair Labor Standards Act does not require breaks.
What's good for the goose is good for the gander.