Dear Greg, thanks for your question. It's not per se illegal to establish an English only policy at work and such policies can definitely be legally implemented, but you have to be very careful how you phrase your policy and how you enforce it because such regulations can run afoul of Title VII of the Civil Rights Act of 1964. Title VII is basically enforced through complaints filed with the EEOC (Equal Employment Opportunity Commission) before a private lawsuit can get filed.

The basic rule is that English-only rules can be adopted only for nondiscriminatory reasons, and the use must relate to specific circumstances in the workplace. In addition, you as an employer have to balance the business justifications for the rule against the possible discriminatory consequences. I think your argument specific circumstance would be that other employees feel uncomfortable when English is not spoken and there is a necessity of effectively running your business. It's probably possible for you to implement a policy but it is going to be hard to enforce, your specific circumstances aren't necessarily the strongest justification as demonstrated by the examples below, and it is going to be hard to draft tightly enough. I would suggest you just point out to your employees that communication can be hampered between them if everyone doesn't understand what's being said, without trying to formally adopt a policy or force them to adhere to it. If you go with the policy route, definitely make sure to retain a NY barred lawyer to draft your policy, which should only take a few hours. Hope this helps!

The EEOC's website provides a great overview of your exact issue so I'm going to literally cut and paste what's written there: (the below is all from http://www.eeoc.gov/policy/docs/national-origin.html#VC)

1. Application of Title VII to English-Only Rules

Title VII permits employers to adopt English-only rules under certain circumstances. As with any other workplace policy, an English-only rule must be adopted for nondiscriminatory reasons. An English-only rule would be unlawful if it were adopted with the intent to discriminate on the basis of national origin. Likewise, a policy that prohibits some but not all of the foreign languages spoken in a workplace, such as a no-Navajo rule, would be unlawful.

EXAMPLE 19 ENGLISH-ONLY RULE: INTENTIONAL DISCRIMINATION

XYZ Textile Corp. adopts a policy requiring employees to speak only English while in the workplace, including when speaking to coworkers during breaks or when making personal telephone calls. XYZ places Hispanic workers under close scrutiny to ensure compliance and replaces workers who violate the rule with non-Hispanics. Jose, a native Spanish speaker, files a charge with the EEOC alleging that the policy discriminates against him based on his national origin. XYZ states that the rule was adopted to promote better employee relations and to help improve English skills. However, the investigation reveals no evidence of poor employee relations due to communication in languages other than English. Nor are proficient English skills required for any of the positions held by non-native English speakers. Because XYZ's explanation is contradicted by the evidence, the English-only rule is unlawful.(47)

Even where an English-only rule has been adopted for nondiscriminatory reasons, the employer's use of the rule should relate to specific circumstances in its workplace.(48) An English-only rule is justified by "business necessity" if it is needed for an employer to operate safely or efficiently. The following are some situations in which business necessity would justify an English-only rule:

• For communications with customers, coworkers, or supervisors who only speak English
• In emergencies or other situations in which workers must speak a common language to promote safety
• For cooperative work assignments in which the English-only rule is needed to promote efficiency
• To enable a supervisor who only speaks English to monitor the performance of an employee whose job duties require communication with coworkers or customers

The following is an example of a narrowly crafted English-only rule promoting safety in the workplace.

EXAMPLE 20 PERMISSIBLE ENGLISH-ONLY RULE: PROMOTING SAFETY

XYZ Petroleum Corp. operates an oil refinery and has a rule requiring all employees to speak only English during an emergency. The rule also requires that employees speak in English while performing job duties in laboratories and processing areas where there is the danger of fire or explosion. The rule does not apply to casual conversations between employees in the laboratory or processing areas when they are not performing a job duty. The English-only rule does not violate Title VII because it is narrowly tailored to safety requirements.(49)

1. Best Practices

In evaluating whether to adopt an English-only rule, an employer should weigh business justifications for the rule against possible discriminatory effects of the rule. While there is no precise test for making this evaluation, relevant considerations include:

• Evidence of safety justifications for the rule
• Evidence of other business justifications for the rule, such as supervision or effective communication with customers
• Likely effectiveness of the rule in carrying out objectives
• English proficiency of workers affected by the rule(50)

Before adopting an English-only rule, the employer should consider whether there are any alternatives to an English-only rule that would be equally effective in promoting safety or efficiency.

EXAMPLE 21 ENGLISH-ONLY RULE: NONDISCRIMINATORY ALTERNATIVE

At a management meeting of XYZ Electronics Co., a supervisor proposes that the company adopt an English-only rule to decrease tensions among its ethnically diverse workforce. He reports that two of the employees he supervises, Ann and Vinh, made derogatory comments in Vietnamese about their coworkers. Because such examples of misconduct are isolated and thus can be addressed effectively under the company's discipline policy, XYZ decides that the circumstances do not justify adoption of a facility-wide English-only rule. To reduce the likelihood of future incidents, XYZ supervisors are instructed to counsel line employees about appropriate workplace conduct.(51)

An employer should ensure that affected employees are notified about an English-only rule and the consequences for violation. The employer may provide notice by any reasonable means under the circumstances, such as a meeting, e-mail, or posting. In some cases, it may be necessary for an employer to provide notice in English and in the other native languages spoken by its workers. A grace period before the effective date of the rule also may be required to ensure that all workers have received notice.