The Faculty of Advocates says proposals to close 16 sheriff and justice of the peace courts would make courts less accessible as people will have to travel further and incur greater travel and accommodation costs.
The lawyers' association also believes the plans could mean court proceedings being disrupted when witnesses, victims or the accused cannot get to court on time due to greater travelling distances.
A consultation on the restructuring has been carried out by the Scottish Court Service (SCS). The proposals would also stop high court business being held outwith Glasgow, Edinburgh and Aberdeen, and are expected to save £5 million a year.
A spokesman for the Faculty of Advocates said: "A properly funded system of courts, accessible to the public, is an essential characteristic of a society governed by the rule of law.
"The rule of law requires that barriers to access to justice should, where possible, be reduced and removed.
"Access to justice has various aspects, but one of them is geographical. The current court system makes available to the people of Scotland, throughout Scotland, local courts of wide jurisdiction.
"Litigants can bring cases and persons accused of crime can be tried in a court which is relatively convenient to them and to the witnesses and others who may be interested in the case.
"The proposals to introduce centres of specialism for sheriff court business in the limited number of centres identified in the consultation would have an adverse impact on the accessibility of justice in rural parts of mainland Scotland."
He added: "It would impose on witnesses, accused persons and victims of crime greater costs in terms of travel time and travel costs and in some cases, no doubt, costs of accommodation."
The faculty highlighted a number of situations which would cause problems, including a case from Thurso being heard in Inverness that would involve a 109-mile trip for parties and witnesses, taking almost two hours 15 minutes each way.
A case from Stranraer heard at Ayr Sheriff Court would mean a 50-mile, 75-minute trip each way.
The spokesman added the plans would cause particular problems for the disabled, the elderly and parents of school-age children. He said: "Parents who are required to attend a local court at, say 9.45am, are likely to be able to accommodate dropping off a child at nursery or school before attending court. If the court is more remote from their school, this will not be possible."
The faculty also said the standard practice of placing some witnesses such as police officers and experts on standby so as not to keep them waiting at court too long may not be pos-sible if the court is too far away. He said lengthy travel times could result in people failing to appear on time, disrupting court business.
And, he said: "In rural areas, where there may be little choice as far as public transport is concerned, the accused, victims of crime and witnesses may also have to travel to and from court on the same bus or train, with the attendant risk of confrontation between rival camps and interference with witnesses."
An SCS spokesman said consultation responses will be analysed this month and next, with a report in April setting out the SCS response to the consultation and firm proposals for future court structures.
A decision on court closures would be a matter for the Scottish Parliament and would require legislation.
Other groups have voiced opposition to the moves.
North Lanarkshire Council is concerned at the proposed closure of Motherwell, Coatbridge and Cumbernauld justice of the peace courts and the transfer of their business to Hamilton and Airdrie sheriff courts.
The Federation of Small Businesses says plans to re-organise courts will damage footfall and hit jobs in the areas where the courts are due to shut.