Certiorari dismissed as improvidently granted.

Federal immigration policy, as expressed in the Immigration Reform and Control Act of 1986, foreclosed the National Labor Relations Board from awarding backpay to an undocumented alien who was never legally authorized to work in the United States.

In order to demonstrate a Sixth Amendment violation where the trial court fails to inquire into defense counsel's potential conflict of interest about which the court knew or reasonably should have known, the defendant must establish that the conflict adversely affected counsel's performance.

The Social Security Administration's interpretations of the Social Security Act provisions that authorize payment of Social Security disability benefits and Supplemental Security Income to individuals who have an "inability to engage in any substantial gainful activity by reason of any medically determinable . . . impairment . . . which has lasted or can be expected to last for a continuous period of not less than 12 months," 42 U. S. C. §423(d)(1)(A); accord, §1382c(a)(3)(A), are lawful.

Title 42 U. S. C. §1437d(l)(6)'s plain language unambiguously requires public housing lease terms that give local authorities the discretion to terminate the lease of a tenant when a member of the tenant's household or a guest engages in drug-related activity, regardless of whether the tenant knew, or should have known, of that activity.

A Labor Department regulation requiring an employer to grant an additional 12 weeks of leave to an employee who has not been informed that a previous absence would be counted as part of the 12 weeks of leave guaranteed by the Family and Medical Leave Act of 1993 is contrary to the Act and beyond the Labor Secretary's authority.

An Equal Employment Opportunity Commission regulation permitting an otherwise timely filer of a charge alleging job discrimination in violation of Title VII of the Civil Rights Act of 1964 to verify the charge after the time for filing it has expired is an unassailable interpretation of §706 of that Act and is therefore valid.

FERC did not exceed its jurisdiction when it required electric utilities that "unbundle"-i.e., separate-transmission costs from electricity costs when billing their retail consumers to transmit competitors' electricity over their lines on the same terms that the utilities apply to their own transmissions; and FERC's decision not to impose that requirement on utilities that offer only "bundled" retail sales was a permissible policy choice.

The Bankruptcy Code's lookback period, which provides that a discharge does not extinguish certain tax liabilities for which a return was due within three years before the filing of the individual debtor's petition, 11 U. S. C. §507(a)(8)(A)(i), is tolled during the pendency of a prior bankruptcy petition.

A defendant who does not object to a trial court's error under Federal Rule of Criminal Procedure 11 must satisfy Rule 52(b)'s plain-error rule in order to withdraw a guilty plea; a reviewing court may look beyond the plea colloquy to the whole record in determining whether the defendant's substantial rights were affected by the Rule 11 error.