The practice of law would be much more pleasant, many lawyers will tell you over a second Scotch, if it did not require clients. It is one thing to construct an airtight legal argument and quite another to deal with the demands of inconstant human beings. Consider Solicitor General Donald B. Verrilli Jr.’s most prominent client, President Obama. In May, in announcing his support for same-sex marriage, Mr. Obama said the issue should be decided state by state. In his Inaugural Address last month, Mr. Obama seemed to make a case for a more national approach. The timing was awkward. Mr. Verrilli is in the midst of considering what to tell the Supreme Court in a pair of momentous same-sex marriage cases to be argued in March. Just days before the inauguration, he met with lawyers challenging California’s ban on same-sex marriage, who urged him to weigh in on their side. He was noncommittal, but his client’s public marching orders until then had suggested that he should sit that one out.