Caroline Flanagan, the society's president, will tell the society's annual meeting that a proposed four-fold increase in fines for firms who have complaints upheld against them, and costs incurred by a new independent complaints body, could deter many rural practices from giving advice on matters such as divorce and conveyancing. These traditionally attract a high level of complaints, but often form the core business for small firms in country areas.
She will highlight several "failings" in the Scottish Legal Complaints Commission as proposed in the new Legal Profession and Legal Aid (Scotland) Bill.
The Law Society is concerned that the commission - which will take over the handling of many complaints from lawyers themselves - is likely to cost more than the current system and will be funded by a levy on the profession as well as individual case fees, which will be payable whether or not a complaint is upheld.
Compensation limits for inadequate professional service have been raised from 5,000 to 20,000. There are concerns that this may be a crippling burden, particularly for small firms on tight margins, which will force many High Street firms to shut down.
The society also believes the proposal that ministers appoint members of the commission's board will compromise the legal profession's independence.
Lawyers gathered in Edinburgh will also hear that the proposals will breach the European Convention on Human Rights as neither those who complain nor solicitors will have a right of appeal. Mrs Flanagan said: "The society questions the bill's constitutionality, its compliance with ECHR and the consequences of access to justice if it is introduced in its present form.
"Consumer interest rather than the public interest is at the heart of the Bill. The cost implications are enormous. My firm belief is that the introduction of the new commission in its presently proposed form will lead to the creation of advice deserts in Scotland.
"Smaller firms may well not be able to continue to practise. Certainly, many firms will question whether they are able to offer legal aid advice at all. Ultimately, if independence is lost and the rule of law threatened, the people of Scotland are the real losers."
But the Executive said change was needed to satisfy consumers' demands for higher standards. A spokeswoman said: "Consumers now look for more from the services they use. They want and deserve more choice, tailored services, transparency and confidence that when things go wrong their complaints will be handled fairly and efficiently.
"Consumers are right to expect high standards of service, and the time is now right for this culture change in our society to be extended into Scotland's legal system."