Here are several situations in which you may be able to get an attorney to represent you for free.
If you've been charged with a crime and cannot afford to hire your own lawyer, you have a constitutional right to an attorney at government expense. At your request, an attorney, often from a public defender's office, can be appointed to represent you when you are formally charged in court with a criminal offense. For more information, see Criminal Defense Lawyer FAQ or the Criminal Law Handbook, by Paul Bergman and Sara Berman (Nolo).
If you have been injured and wish to sue, a lawyer may agree to represent you on a "contingency fee" basis. While the lawyer's services won't be free, you pay the lawyer's fee only when and if she recovers money for you. The attorney takes an agreed-upon percentage of any recovery as her fee. Be aware, however, that even if a lawyer takes your case on a contingency fee basis, you still have to pay costs, which can add up to several thousand dollars. Costs include court filing fees, court reporters' fees, expert witnesses, and jury fees. The good news is that if you win your case, the judge will usually order your adversary to pay you back for these costs.
If you can't afford an attorney, you may qualify for legal aid (often called legal services). Legal aid lawyers are usually government-funded lawyers who represent people with low incomes in a variety of legal situations, including eviction defense, denial of unemployment compensation or other benefits, and consumer credit problems.
If you think you might qualify, look in your telephone directory or ask a local attorney or lawyer referral service for the nearest legal aid office. Because of recent cutbacks in federal funding, you will probably find that legal aid is only available for relatively few types of legal problems and that in some programs waits for services can be lengthy.
If your dispute involves a social justice issue and has wide implications beyond your individual situation, an attorney or public interest legal organization with an interest in that issue may represent you on a "pro bono" (no fee or reduced fee) basis. For example, if your claim involves sexual harassment by an employer, abuse by a spouse or partner, discrimination in housing or employment, freedom of speech or religion, environmental pollution, or access to medical treatment, you may find an attorney or organization willing to represent you pro bono.
Contact a local bar association or even better, a private organization that deals with the kind of problem you face, such as the American Civil Liberties Union, the NAACP Legal Defense Fund, the Natural Resources Defense Council, or the Lambda Legal Defense and Education Fund (gay and lesbian rights).
Before you meet with a lawyer, you might want to learn some common (and perhaps even not-so-common) legal terms. Get Nolo's Plain-English Law Dictionary, now available as a free iPhone app (also compatible with iPod touch).