To be "admitted to the bar" of a particular state is to be licensed to practice law in that state. To see if someone has been admitted to a particular state bar, you can:
(a) Call that state's bar association or the relevant agency or court. You can get find the right organization from A Compilation of State Lawyer Licensing Databases. For New York call 212-428-2800, for Massachusetts call the Board of Bar Overseers at 617-728-8750, for Ohio call the Supreme Court's Office of Attorney Registration at 614-466-1553; for Maryland call the Client Protection Fund of the Bar of Maryland (410-260-3635) or the Clerk of the Court of Appeals (410-260-3635); or
(b) Check the relevant state Web site. Most states -- including Florida, Massachusetts, Maryland, Pennsylvania and Texas -- post a database of admitted attorneys. Direct links to are available from A Compilation of State Lawyer Licensing Databases. If that doesn't work, check the state bar association Web site; links to all states bar sites are available through HG.org Legal Resources; they are also listed on Martindale-Hubbell.
(c) Look in a recently published bar directory using the bar association's lawyer list, such as New York Lawyers Diary and Manual, The New Jersey Lawyer's Diary and Manual, the Maryland Lawyers' Manual, etc.
Absolute Proof: If you need official hard copy proof of an attorney's good standing, call the appropriate court or bar association, as discussed in "(a)," above.
Bar Examination Results: In most states, the names of candidates who passed the bar exam are published in the state's legal newspaper of record. For example, in California, the names are published in the Los Angeles Daily Journal, in New York they are published in the New York Law Journal, in Maryland they are published in the Daily Record and the Maryland Register. The names are also often posted on the newspapers' Web sites, such as the Maryland database going back to 2001 posted by the Baltimore Sun.
The names may also be posted on the Web site of the relevant licensing board. Some of these sites include:
California -- the State Bar of California (www.calbar.org)
Maryland -- the Law Examiners' Web site (www.courts.state.md.us/ble/index.html)
New Jersey -- Board of Bar Examiners (www.njbarexams.org)
New York -- the New York section of Law.com (www.law.com/special/students/ny_barexam/)
Ohio -- the Supreme Court Web site (www.sconet.state.oh.us/Admissions/).
In New York, you can also call the appropriate Department of the Appellate Division. The First Department's number is 212-779-1779, their address is Clerk of the Appellate Division / 60 Madison Avenue, Room 202 / NYC 10010, and they require the request to be made in person or in writing, accompanied by (1) a check payable to the Clerk of the Appellate Division and (2) a SASE.
To find a state: If you don't know the state where an attorney is admitted, check Martindale-Hubbell or the Findlaw Lawyer Directory, since they aren't state-bound, or search for their online resume with a good search engine. You can also try to locate the person's address using public records databases (see "Finding People") and then check with the relevant licensing authority for the state where they live. If necessary, search legal news databases (on Lexis, Westlaw, etc.) for articles about the person and/or case databases for cases they've argued and/or deal databases for deals they've worked on. See also "Finding People."
Admission Requirements: The requirements for bar admission in each state is compiled by the ABA in the Comprehensive Guide to Bar Admission Requirements. You can also find out by calling the state bar or other licensing authority, or the requirements may be posted on their Web site.
In addition to bar admission, certain courts have specific admission requirements (see "Court Admission").
Disciplinary Records: See "Attorneys."
Statistics: Statistics on U.S. bar admissions by state is published in The Lawyer's Almanac.