There are no really truly "objective" metrics by which lawyers are ranked.
One service that rates lawyers is Martindale-Hubbell (which is primarily a directory of lawyers) and makes its ratings into several broad categories based upon a determination of a lawyer's professional reputations among lawyers reached by surveying lawyers who have had dealings with the lawyer in question. Its rating system is as follows:
Historically the Martindale-Hubbell® Peer Review Ratings™ system
utilized an “A - B - C” scale to estimate the legal ability and
ethical standards of an attorney. To qualify for an “A” rating an
attorney had to be reported as “Very High” in their legal ability and
had been practicing for at least 10 years, a “B” rating meant an
attorney was rated “High” and had to be practicing for at least 5
years, and a “C” rating meant that the attorney was rated “fair” with
no limitations on how long they were practicing. A second rating was
also given to go along with the “A - B - C” rating and that was a “V,”
meaning that the attorney's peers stated they had "Very High" ethical
standards. Over the years this transitioned to “AV”, “BV”, and “CV”
ratings - with an “AV” rating meaning that the attorney had reached
the highest of professional excellence and is recognized for the
highest levels of skill and integrity.
Today, Martindale-Hubbell conducts a thorough review of attorneys who
wish to receive a Martindale-Hubbell® Peer Review Ratings™, through a
secure online peer review survey where a lawyer’s ethical standards
and legal ability in a specific area of practice is assessed by their
peers. Once the review process is completed an attorney may receive 1
of the following Martindale-Hubbell® Peer Review Ratings™:
AV Preeminent®: The highest peer rating standard. This is given to
attorneys who are ranked at the highest level of professional
excellence for their legal expertise, communication skills, and
ethical standards by their peers.
Distinguished: An excellent rating for an attorney who has some
experience and is widely respected by their peers for their
professional achievement and ethical standards.
Notable: A rating given to a lawyer who has been recognized by a large
number of their peers for their strong ethical standards
Another, much newer, service that rates lawyers is Avvo. It explains its rating method this way:
How does Avvo calculate the Avvo Rating?
We calculate the rating based on public data we may have collected on
each attorney and the information they have provided in their profile.
The public data we collect comes from a variety of sources, including
public records (state bar associations, regulatory agencies, and court
records) and other published sources on the internet. This
information, however, is not exhaustive, and might not include
additional relevant information that could increase an attorney’s
rating. Attorneys know about their own experience and have the option
to add this information to their profiles – by either claiming their
profile and adding information, or contacting Avvo Customer Care to
provide additional information – and those details will often increase
an attorney’s rating.
Avvo’s mathematical module considers and weights the information
collected and provided to calculate a numerical rating, ranging from 1
to 10. Within the model, we take into account factors that consumers
and legal professionals believe are relevant to an attorney’s
qualifications, including experience, professional achievements, and
disciplinary sanctions.
Other factors are sometimes use to rate lawyers. These include:
The prestige of one's law school (particularly its U.S. News and World Report Law School Ranking), the honors one received in law school (e.g. magna cum laude recognition or specific awards), and whether one was an editor on the principle law review of the law school, a secondary law review of the law school, or did not have law review experience (law review membership is typically based upon first year GPA sometimes together with an application essay). One's undergraduate degree granting institution's prestige is also a factor although much more minor.
Whether one was a judicial clerk after graduating from law school, and if so, with whom. The greatest prestige attaches to lawyers who served as a law clerk for a famous U.S. court of appeals judge followed by serving as a clerk for a U.S. Supreme Court justice. Other clerkships are less prestigious, generally in line with how important the judge is in the legal system.
The prestige of the firm or other employer of the lawyer for which the lawyer has worked. Large law firms, specialty law firms with an elite practice (such as only handling U.S. Supreme Court litigation, or only doing intellectual property cases), and certain governments and non-profits (e.g. the ACLU or the Solicitor-General's office), tend to be more prestigious.
Having clients who are important enhances prestige.
Rightly or wrongly, prestige is evaluated based upon the hourly rate charged by an attorney in arms-length hourly fee agreements.
An involvement of a lawyer high profile or otherwise notable legal cases or business transactions enhances prestige.
Handling higher stakes litigation (more serious crimes in criminal practice, higher dollar amounts in controversy in civil litigation, bigger dollar transactions in business transactions, high value estates in probate practice) enhances prestige, as does working in more sophisticated or intellectually challenging specialties.
Achieving exceptional outcomes in particular cases relative to typical outcomes, when this is known to others, enhances prestige.
Law related legal publications enhance prestige.
A history of professional license discipline, court sanctions, and/or unsuccessful outcomes in malpractice lawsuits usually reduces prestige.
Years of experience as a practicing lawyer enhances prestige.
Status as an owner or co-owner of a law practice enhances prestige.
More prestigious lawyers typically spend a larger share of their time interacting with others outside their law firms, especially in negotiation settings.
Also, keep in mind that while the U.S. with some narrow exceptions, doesn't license lawyers based upon particular specialties, almost all lawyers specialize to some extent. A law who is well qualified in their specialty is not necessarily well qualified outside areas where they have extensive relevant experience.