AS THE United States has negotiated with Vietnam over a trade deal intended to elevate the rule of law, the rule of law has been steadily eroding inside Vietnam. Secretary of State John F. Kerry, who is scheduled to visit the country this weekend, can no longer brush aside this fundamental contradiction in policy.

Nguyen Thi Tram highlighted the contradiction during a visit to Washington this week. Two of her sons, Le Quoc Quan and Le Dinh Quan, have been sentenced to prison for peaceful advocacy of democracy and free speech. Now a niece has been arrested as well, Ms. Nguyen told us, and her entire family has been assessed ruinous fines. Her sons have been beaten and held in solitary confinement; she has not been allowed to visit one of them since his detention a year ago.

Her experience is not anomalous. This year has seen an “intensifying crackdown on free speech,” Sen. Robert Menendez (D-N.J.), chairman of the Foreign Relations Committee, recently wrote to Mr. Kerry. At least 63 people have been convicted for free speech acts in 2013, according to Human Rights Watch (HRW). After promising improvements in order to win membership on the U.N. Human Rights Council, Vietnam has gone backward. An amended constitution was adopted Nov. 28 that has further “tightened the ruling party’s grip,” said Brad Adams, HRW’s Asia director.

Meanwhile the United States is working hard to complete a multinational trade deal, the Trans-Pacific Partnership, that is meant to set a new standard for economic agreements. China is pointedly not included because it does not meet the pact’s rule-of-law aspirations. Yet Vietnam, which follows China’s policy of seeking foreign investment while repressing its own citizens’ rights — no independent trade unions allowed — would be a charter member.

“U.S. officials are aware of these cases, and they do bring them up when they talk to the Vietnamese government,” Trinh Hoi, a democracy advocate, told us, referring to imprisoned activists such as Ms. Nguyen’s sons. “But I don’t think it is a top priority of the administration right now.”

Mr. Kerry should fix that. A trade deal, if one is reached, would face skepticism in Congress even if it is, as advertised, an agreement among nations ready to respect the rule of law. If one of the major economies involved is becoming steadily more repressive, the pact’s chances in Congress would be further diminished.

Rep. Edward R. Royce (R-Calif.), chairman of the House Foreign Affairs Committee, cautioned Mr. Kerry in a letter this week that “a closer relationship between the United States and Vietnam must be conditioned on improvements in the Vietnamese government’s respect for the basic freedoms of its citizens.” Unconditional release of Ms. Nguyen’s sons would be a good place to start.