Who says Fridays get all the fun? Whether its entrepreneurial clients or millennial lawyers driving the change, law firms are increasingly putting the casual in business casual.

Dechert is the latest firm to expand its definition of acceptable workplace attire. Management at the firm announced on Tuesday a new business casual dress code that means lawyers and staff can now wear jeans any day of the week, if they so choose.

"My suspicion is there are a lot of firms that are much more relaxed than they used to be," said Susan Saltonstall Duncan, founder of Rainmaking Oasis.

Dechert's chief talent officer, Alison Bernard, said the firm already had a business casual policy, but that has now been slightly relaxed to include jeans. Some offices within the firm had already allowed lawyers and staff to wear jeans on certain days or parts of the year, Bernard said, but there was a desire for a more consistent policy.

"This is just trying to make life easier for people, make people more comfortable, more innovative and letting our talent do their best work," Bernard said.

Still, she noted, lawyers will be expected to wear business attire for court appearances, arbitration, deposition and other specific events or meetings that call for a more formal appearance.

"Our guidance was always adapt to your clients' norms," Bernard said.

The corporations that many law firms count as clients have largely loosened their own views on professional attire. Goldman Sachs recently made headlines with its switch to a more flexible dress code.

It's a movement that started about two decades ago, as technology companies became more dominant and some law firms started imitating the entrepreneurs they serve, Duncan said. Around then, many firms began implementing casual Fridays, and those that serve startup clients may have been quicker to adopt a more casual policy throughout the week.

"There were a number of firms that relaxed the dress code because the client base felt uncomfortable," she said. With regard to that reasoning, cutting back on the dress code expectations makes sense.

"As a consultant… I always say mirror the client," she said.

But a lot of firms are making changes to their dress codes based on the lawyers rather than the clients, Duncan noted. Young lawyers tend to favour informality in the workplace generally and that includes their clothing, she said, but that may not fit at a firm that serves more traditionally minded clients. It will be interesting to track the longer-term effects on firms' reputations, she said.

Loosening dress codes is an appeal to the millennial generation, said Darin Morgan, managing partner of Major, Lindsey & Africa's Philadelphia office, who related the move to an increase in flexible work schedules, remote work arrangements and other perks.

Law firms were under-hiring for years, but now that they're busier and need more lawyers, there is a shortage of mid-level associates with strong skillsets, Morgan said. So they're making fierce efforts at recruitment and retention.

"They're listening to their associates much better than before," he said. "What they care about the most is that the work gets done… to keep the firm as profitable as possible."

Morgan said he's inclined to agree with that philosophy. The only potential downside, he said, is if someone "takes it too far and happens to be seen by a very conservative client who happens to be at the firm that day".

Bernard noted the same, which is why Dechert rolled out an added perk with its new jeans policy – a garment bag for storing a suit or other business attire within the office for unexpected meetings or visits.

At Dechert, Bernard said, client policies and young lawyers' expectations were among the drivers of the change. The firm has made several enhancements for attorneys and staff in recent years, including improved parental leave and a wellness initiative.

"Compensation is always important, prestige is important, but the culture of a firm is one of the biggest drivers of career choice," Bernard said. "I think these are major, major drivers of how people are choosing where they want to work."