Yesterday was a tough one for Johnson & Johnson.

Not only did the New Brunswick, N.J.-based conglomerate post second-quarter sales and earnings declines, but it also revealed that New Jersey Attorney General Anne Milgram subpoenaed its DePuy Orthopaedics subsidiary for documents related to the “financial interests of clinical investigators who performed clinical studies for DePuy Orthopaedics, Inc. and DePuy Spine, Inc.,” according to a federal Securities and Exchange Commission filing.

J&J’s Q2 sales were off 7.4 percent, falling to $15.24 billion during the three months ended June 28, compared with $16.45 billion during the same period last year.

Net earnings slipped 3.6 percent to $3.21 billion for the quarter, compared with $3.33 billion during the second quarter of 2008.

Total sales for the company’s medical devices and diagnostics unit were also off during the period, falling 3.1 percent to $5.89 billion, compared with $6.07 billion during Q2 2008.

The division’s U.S. sales were up nearly 2 percent, however, rising to $2.78 billion compared with $2.72 billion during the year-ago period. But international sales fell to $3.11 billion, down 7.2 percent compared with $3.35 billion during the 2008 second quarter.

Even so, the MDD segment managed to post a 22.7 percent increase in operating profit.

The DePuy businesses saw quarterly sales remain relatively flat, slipping less than a percent to $1.32 billion compared with $1.33 billion during the same period in 2008.

The subpoena action in Jersey, which was filed in May, marks another round of legal action related to medical devices in the Garden State.

Milgram subpoenaed J&J’s Minneapolis-based rival Medtronic Inc. earlier this year, seeking documents on clinical studies and research and related payments to physicians, according to the Wall Street Journal (paid).

And DePuy was one of five orthopedic device makers involved in a federal case in 2007 that saw four of them pony up $311 million (DePuy’s share was $85 million, according to the Journal).