In recent years, the U.S. Supreme Court has handed down some employment law decisions that, quite frankly, have had little practical impact beyond the parties to that case. But two employment law decisions handed down in the last week of the 2012-2013 term have quite significant implications for employment discrimination law — consequences that are favorable to employers. The holding in each case — one relating to retaliation and the other relating to workplace harassment — will make it harder for plaintiffs to assert successful claims.

Effective enforcement of employment discrimination law requires that stringent sanctions be imposed against companies that retaliate against employees who object to perceived unlawful acts. That being so, the Supreme Court has, over the last few years, given wide berth to retaliation claimants — finding retaliation liability under statutes that do not explicitly reference retaliation, CBOCS West Inc. v. Humphries, 553 U.S. 442 (2008); finding protected conduct by participating in a company investigation of discrimination claims brought by co-workers, Crawford v. Metropolitan Gov't of Nashville & Davidson County, Tenn., 555 U.S. 271 (2009); and accepting the Equal Employment Opportunity Commission's (EEOC) broad definition of retaliation, Burlington N. & Santa Fe Ry. Co. v. White, 548 U.S. 53 (2006). Under White, victims of retaliation need not prove they suffered some material, adverse job action as a consequence of their protected activity; they need only show that a reasonable worker in their situation would "likely [be] dissuaded" from protesting the perceived discrimination if she had known it would have resulted in the undesired consequence — such as a loss of flexibility in work scheduling, as opposed to more "tangible" actions such as termination or the denial of a promotion. See id. at 68-70.

In University of Texas Southwestern Med. Center v. Nassar, No. 12-484 (2013), the Supreme Court held that plaintiffs alleging retaliation under Title VII of the Civil Rights Act of 1964 must establish that their protected activity was a but-for cause of the alleged adverse action taken by their employer. This standard of causation, which the court called "the standard requirement of any tort claim," generally requires "the plaintiff to show 'that the harm would not have occurred' in the absence of — that is, but for — the defendant's conduct." Slip op. at 5-6.

It is fair to say that retaliation may now be the predominant claim being asserted under federal employment discrimination laws. During the past 15 years, retaliation claims filed with the EEOC have more than doubled from 18,198 (in 1997) to 37,836 (in 2012). And, in 2012, allegations of retaliation were asserted in 38 percent of all EEOC charges. That was higher than for those charges alleging discrimination on the basis of race (34 percent) or gender (31 percent). It is also quite common for plaintiffs to prevail on their retaliation claim even while losing the underlying claim of discrimination, as occurred in Nassar itself.

Retaliation claims are also easy to allege and hard to defend. Protected activity, for purposes of a Title VII retaliation claim, includes opposing conduct that the plaintiff reasonably believed was discriminatory, even if no illegal discrimination actually occurred. Clark County School Dist. v. Breeden, 532 U.S. 268 (2001). A prima facie case of retaliation can be established if the only evidence of causation was that the challenged employer conduct occurred shortly after its managers knew of the plaintiff's protected activity. And, as noted, virtually any nontrivial harm is enough to impose liability for retaliation.

Moreover, companies can often rebut allegations of a discriminatory motive by showing that they treated other employees within the protected classification favorably, even though the plaintiff was adversely affected — for example, that other women in the company were promoted even though the plaintiff was not. But there is not a ready comparison class of similarly situated objectors to alleged discrimination who were not adversely treated — and, if there were, what company would want to present that defense to a jury?

The Nassar case brings needed balance to anti-retaliation law. The plaintiff in such cases need not, even under Nassar, show that retaliation was the sole motive for the employer's action, but if he cannot show that " 'the harm would not have occurred' in the absence" of his opposition to perceived discrimination, the retaliation claim cannot survive.

In much the same way, the Supreme Court's decision in Vance v. Ball State University, No. 11-556 (2013), brings needed balance to the law of workplace harassment by narrowing the scope of alleged harassers for whom the company is vicariously liable. Since two landmark rulings in 1998 — Burling­ton Industries Inc. v. Ellerth, 524 U.S. 742 (1998), and Faragher v. Boca Raton, 524 U.S. 775 (1998) — liability for sexual harassment at work has critically depended on whether the alleged harasser was a supervisor or co-worker of the victim. Yet, having created the distinction between supervisor and nonsupervisor harassment, it was only in Vance that the court defined who is a supervisor.

Under now well-settled law, an employer is liable for a discriminatory hostile work environment engendered by the victim's co-workers only if it was negligent with respect to the offensive behavior, usually by failing to take appropriate corrective action after it knew (or should have known) that the harassment was occurring. But employers are vicariously liable for discriminatory workplace environments attributable to a supervisor unless they can establish as an affirmative defense both that they took reasonable steps to prevent or correct the harassment and that the plaintiff unreasonably failed to take advantage of the preventive or corrective opportunities provided.

The Supreme Court held in Vance that, for purposes of vicarious liability for harassment, a "supervisor" is only someone empowered by the employer "to take tangible employment actions against the victim," such as the power to hire, fire, demote, promote, transfer, discipline or reassign. Slip op. at 8-9. In so holding, the court rejected what it called the "nebulous definition" favored by the EEOC and adopted by certain courts of appeals, which had extended supervisor status to co-workers who exercised significant dir­ection over another daily's work. Id. at 9.

As the Vance majority noted, modern organizations have abandoned highly hierarchical structures in favor of team-based approaches where, at various times, different members of the team with specific areas of experience or expertise will direct the work of other team members. Allowing vicarious liability to depend on whether the accused employee directed the victim's work would be particularly difficult to apply in those circumstances. In contrast, if the standard is based on the exercise of tangible employment actions, then, as the court saw it, the question of supervisory status, if contested, "can very often be resolved as a matter of law before trial." Id. at 22.

Employer liability for workplace harassment is open-ended, as it is for retaliation. There is, for example, effectively no statute of limitations period for a supervisor-created hostile work environment. No matter how long ago the offensive behavior began, the employer is liable for it all, provided only that some part of the pattern of harassing behavior occurred within the applicable limitations period. National R.R. Passenger Corp. v. Morgan, 536 U.S. 101, 118 (2002). And, although actionable harassment under Title VII occurs only if the offensive behavior is "severe or pervasive," Harris v. Forklift Systems Inc., 510 U.S. 17, 21 (1993), courts will typically allow that issue go to the jury in virtually every case as long as the behavior at issue extends beyond "ordinary socializing of the workplace." Oncale v. Sundowner Offshore Services Inc., 523 U.S. 75, 81 (1998). Furthermore, although the Supreme Court cases have addressed only sexual harassment (except in Vance, where the actionability of an alleged racial harassment was expressly left undecided), the lower courts have found liability for hostile work environments based on virtually all protected categories — sex, race, religion, age and disability.

When the employer grants to supervisors power over the economic well-being of other employees, vicarious liability for abuse of that power is fitting. But when the putative supervisor is a co-worker who from time to time directs the victim's work, employers are liable, under Vance, only if they negligently allow discriminatory workplace hostility to occur or persist.

Supreme Court decisions issued simultaneously with Vance and Nassar stole the national headlines. But for the employment law practitioner, those two cases were among the most far-reaching of the high court decisions of the past few years.

Michael Starr is a labor and employment law partner in the New York office of Holland & Knight. Edward C. Frischling, an associate at that firm, assisted in the ­preparation of this article.