As we've seen recently with the impeachment proceedings against President Donald Trump, congressional investigations are very different than matters with which most lawyers are familiar. They are a blend of civil litigation, criminal inquiry, academic constitutional debate, public relations and politics. The litigation playbook most lawyers follow does not apply and actually can be counterproductive.

So what should you do if Congress wants to talk to your client? Here are some insider tips.

The Rules of the Road

Once a lawyer has determined that a client will respond to a request for testimony or information, either voluntarily or because a subpoena was served, the next step is to contact the congressional staff.

Remember that the ordinary rules of civil discovery don't apply—the rules of judicial procedure are not applicable to congressional inquiries. There is no assigned magistrate judge to call to pare back document requests. After all, Congress isn't bound by the courts' common law practices and isn't obligated to recognize protections like attorney-client privilege, work product doctrine or other nonconstitutional privileges.

Confidentiality of sensitive documents is a worthy concern for clients. Fortunately, Congress generally respects the rights of parties to keep legal advice confidential and rarely will compel a party to produce clearly privileged documents.

Still, Congress has nearly limitless power to investigate anything within the "legitimate legislative sphere," and based on the separation of powers doctrine, the federal judiciary has "the duty of not lightly interfering with Congress' exercise of its legitimate powers." It follows that courts are unable to order a congressional committee to refrain from publishing congressionally subpoenaed documents, as congressional members are legislatively immune under the Constitution. This means clients have no effectual relief for unwanted disclosure of their secrets.

This doesn't mean clients should ignore congressional authority in order to maintain the confidentiality of privileged information, but lawyers should recognize that they are relying on the discretion of the staffers to protect a client's interests. Most committee counsel staff are sophisticated and generally will be understanding with privilege claims. Try to broker terms for privilege logs, redactions and, if necessary, the appointment of a special master to review withheld documents.

However, be judicious and remember Congress is its own branch of government with its own rules and that your client is essentially asking for an accommodation under those rules. Committee counsel initially may challenge an assertion of privilege or protection. A discovery dispute letter that would peel the varnish off the desk of opposing counsel would be the wrong response here. Instead, make a phone call, introduce yourself, and negotiate a mutually satisfactory result.

Congress has little desire to see the scope of common law privileges tested in the courts. The courts are equally quick to dodge these questions. Try to learn what the committee counsel's goals are for the hearing and see if your client can meet those goals, or at least in part. Request an audience to discuss concerns about breadth, privilege or other sensitive issues.

Giving Testimony

If testimony is requested, again, remember that this is not civil litigation. Respect matters. Trying to substitute lower-level employees when the client's CEO or chairman is requested for a public hearing often is viewed as disrespectful by committees, even if the employee has a better handle on an issue. If testimony will be given in closed session or in deposition with staff, identifying and suggesting the most knowledgeable person will be better received.

Furthermore, be thoughtful with scheduling requests to avoid the perception of having more important things to do than appearing before Congress. Regardless of the setting, remind witnesses that false statements to Congress are crimes, whether or not a statement is given under oath. If your client lies in an unsworn setting, it will matter little for your client that the charge is a "false statement to Congress" rather than "perjury."

For public hearings, help your client draft an opening statement at the full length allowed under committee rules. Hearings are of limited duration, and every minute spent talking from a prepared script is a minute not spent answering questions that could be contentious. Also, research the members of the committee to try to predict their interests and possible areas of inquiry.

A few days prior, run a mock hearing and show videos of successful public hearings to familiarize your client with the process. Public hearings and congressional depositions and interviews are very different from depositions or trial testimony in court. For example, the attorney generally cannot object, interrupt questioning or "redirect." Yet, these differences work to your client's advantage, too.

You can suggest favorable questions to "friendly" staffers or committee members. Long, narrative-style answers to short questions are generally allowed in all but the most adversarial settings. The time for a hearing is finite, so prepare your client to give lengthier answers to easy, favorable or noncontroversial questions, which you ideally have shared in advance. Consider preparing answers or opening remarks that address the anticipated difficult questions in keeping with the nature of the proceeding (public or closed-door). Also remember that one-word answers can make even a truthful witness look suspicious in a congressional setting, which any resulting media coverage may regrettably also reflect.

If Congress wants to talk to your client, nuances of the situation will depend on the subject, politics and timing. The most important point for outside-the-Beltway lawyers is to recognize that your typical litigation playbook may need to be modified, if not tossed aside.

Robert N. Driscoll leads the Washington, D.C., office for McGlinchey Stafford and serves as co-chair of its white-collar/government investigations group.