Pakistani police arrested the son of a former prime minister on Friday in connection with a drugs case, the latest twist in a power struggle between the increasingly assertive Supreme Court and the ruling party.
The feud could hurt Pakistan's young democracy and distract the government from tackling widespread poverty, a Taliban insurgency and chronic power shortages.
Police said they detained Ali Musa Gilani ahead of his scheduled court appearance.
In June, the Supreme Court removed his father, Yusuf Raza Gilani, from his post as prime minister over his refusal to re-open corruption cases against President Asif Ali Zardari.
The current prime minister, Raja Pervez Ashraf, could face the same fate if he too fails to re-open the corruption cases against Zardari.
Television stations showed police dragging Ali Musa Gilani from his vehicle and handcuffing him.
He is accused of pressuring Health Ministry officials to exceed export quotas for ephedrine, an ingredient for cough medicine which can also be used to make ecstasy.
Chief Justice Iftikhar Chaudhry has earned a reputation for taking on Pakistan's most powerful figures, including members of the ruling Pakistan People's Party (PPP) and the military, which has ruled the country for more than half of its history.
Critics say he meddles in areas outside the Supreme Court's jurisdiction and creates political tensions that fuel instability in nuclear-armed Pakistan, a strategic U.S. ally.
Chaudhry himself has come under scrutiny.
A real estate tycoon, Malik Riaz, accused the chief justice of turning a blind eye to his son's alleged financial practices. Riaz said he has given more than $3 million to the top judge's son, Arsalan Iftikhar Chaudhry, who denies the allegations.