An employer must be lawful, but the law doesn't require that an employer be nice. It may be sexual harassment or discrimination, though, if a male supervisor takes a harder stance with female employees than he does with male employees.
To prove an age discrimination case, an employee must show that:
The ADA requires that an employer make reasonable accommodation for an employee who is considered a "qualified individual with a disability". Reasonable accommodation contemplates that an employee is qualified and able to perform the job for which he or she is applying. If not, the employer need not reasonably accommodate the disability.
The ADA does not require an employer to create new jobs, displace existing employees from their positions or violate other employees' rights under a collective-bargaining agreement or other non-discriminatory policy in order to accommodate an otherwise disabled individual under the ADA. If an employee is not otherwise qualified and able to perform satisfactorily in a position, he will not prevail in proving a duty to accommodate.
Punitive damages are available to age discrimination claimants, but not in every case. Punitive damages, by their very nature, are designed to punish. So the aggrieved party must prove that the defendant acted with "actual malice". The employee must show that the employer's conduct rose to the level of outrageous, flagrant, or even criminal conduct to support a finding of actual malice. It's a difficult test to pass, but there are employees who can meet this standard. It's clearly a fact-specific, case-by-case analysis.